Add java doc comments

Use try-with resource when using CloseableHttpClient
Refactor few variable and method names

components/application-mgt/io.entgra.application.mgt.common/src/main/java/io/entgra/application/mgt/common/exception/IdentityServerManagementException.java

@@ -21,6 +21,12 @@ package io.entgra.application.mgt.common.exception;
  * Exception that will be thrown if any error occurs while calling identity server services .
  */
 public class IdentityServerManagementException extends ApplicationManagementException {
+
+    public IdentityServerManagementException(String message, Throwable throwable) {
+        super(message, throwable);
+        setMessage(message);
+    }
+
     public IdentityServerManagementException(String message) {
         super(message);
         setMessage(message);

components/application-mgt/io.entgra.application.mgt.common/src/main/java/io/entgra/application/mgt/common/services/ApplicationManager.java

@@ -100,6 +100,12 @@ public interface ApplicationManager {
      */
     <T> ApplicationDTO uploadReleaseArtifactIfExist(T app) throws ApplicationManagementException;
 
+    /**
+     * Check if public app release packageName is valid (I.E invalid if packageName already exists)
+     *
+     * @param packageName name of the application release package
+     * @throws ApplicationManagementException if package name is invalid
+     */
     void validatePublicAppReleasePackageName(String packageName) throws ApplicationManagementException;
 
     /**
@@ -169,6 +175,13 @@ public interface ApplicationManager {
      */
     void deleteApplicationRelease(String releaseUuid) throws ApplicationManagementException;
 
+    /**
+     * Use to delete application artifact files (For example this is useful to delete application release artifacts
+     * (I.E screenshots) when an application is deleted)
+     *
+     * @param directoryPaths directory paths that contains release artifacts (I.E screenshots)
+     * @throws ApplicationManagementException if error occurred while deleting artifacts
+     */
     void deleteApplicationArtifacts(List<String> directoryPaths) throws ApplicationManagementException;
 
     /**
@@ -220,6 +233,13 @@ public interface ApplicationManager {
                                          ApplicationType type)
             throws ApplicationManagementException;
 
+    /**
+     * Get application and all application releases associated to the application for the given application Id
+     *
+     * @param applicationId Application Id
+     * @return {@link ApplicationDTO}
+     * @throws ApplicationManagementException if error occurred application data from the database.
+     */
     ApplicationDTO getApplication(int applicationId) throws ApplicationManagementException;
 
     /**
@@ -292,7 +312,8 @@ public interface ApplicationManager {
     void updateApplicationArtifact(String deviceType, String uuid,
             ApplicationArtifact applicationArtifact) throws ApplicationManagementException;
 
-    /***
+    /**
+     * Use to update existing enterprise app release
      *
      * @param releaseUuid UUID of the application release.
      * @param entAppReleaseWrapper {@link ApplicationReleaseDTO}
@@ -302,22 +323,47 @@ public interface ApplicationManager {
     ApplicationRelease updateEntAppRelease(String releaseUuid, EntAppReleaseWrapper entAppReleaseWrapper,
                                            ApplicationArtifact applicationArtifact) throws ApplicationManagementException;
 
+
+    /**
+     * Use to update existing public app release
+     *
+     * @param releaseUuid UUID of the application release.
+     * @param publicAppReleaseWrapper {@link ApplicationReleaseDTO}
+     * @param applicationArtifact {@link ApplicationArtifact}
+     * @return If the application release is updated correctly True returns, otherwise retuen False
+     */
     ApplicationRelease updatePubAppRelease(String releaseUuid, PublicAppReleaseWrapper publicAppReleaseWrapper,
                                            ApplicationArtifact applicationArtifact) throws ApplicationManagementException;
 
+    /**
+     * Use to update existing web app release
+     *
+     * @param releaseUuid UUID of the application release.
+     * @param webAppReleaseWrapper {@link ApplicationReleaseDTO}
+     * @param applicationArtifact {@link ApplicationArtifact}
+     * @return If the application release is updated correctly True returns, otherwise retuen False
+     */
     ApplicationRelease updateWebAppRelease(String releaseUuid, WebAppReleaseWrapper webAppReleaseWrapper,
                                            ApplicationArtifact applicationArtifact) throws ApplicationManagementException;
 
+    /**
+     * Use to update existing custom app release
+     *
+     * @param releaseUuid UUID of the application release.
+     * @param customAppReleaseWrapper {@link ApplicationReleaseDTO}
+     * @param applicationArtifact {@link ApplicationArtifact}
+     * @return If the application release is updated correctly True returns, otherwise retuen False
+     */
     ApplicationRelease updateCustomAppRelease(String releaseUuid, CustomAppReleaseWrapper customAppReleaseWrapper,
                                               ApplicationArtifact applicationArtifact) throws ApplicationManagementException;
 
-    /***
+    /**
      * To validate the application creating request
      *
      */
     <T> void validateAppCreatingRequest(T param) throws ApplicationManagementException, RequestValidatingException;
 
-    /***
+    /**
      *
      * @throws ApplicationManagementException throws if payload does not satisfy requirements.
      */

components/application-mgt/io.entgra.application.mgt.core/src/main/java/io/entgra/application/mgt/core/identityserver/serviceprovider/impl/WSO2IAMSPApplicationService.java

@@ -65,8 +65,7 @@ public class WSO2IAMSPApplicationService implements ISServiceProviderApplication
         String uriString = constructAPIUrl(identityServer);
         uriString += Constants.FORWARD_SLASH + spAppId;
         req.setURI(HttpUtil.createURI(uriString));
-        CloseableHttpClient client = HttpClients.createDefault();
+        try (CloseableHttpClient client = HttpClients.createDefault()) {
-        try {
             HttpResponse response = invokeISAPI(identityServer, client, req);
             String responseBody = HttpUtil.getResponseString(response);
             if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
@@ -82,16 +81,17 @@ public class WSO2IAMSPApplicationService implements ISServiceProviderApplication
         } catch (IOException e) {
             String msg = "Error occurred while calling SP Applications API. Make sure identity server is up and running";
             log.error(msg, e);
-            throw new IdentityServerManagementException(msg);
+            throw new IdentityServerManagementException(msg, e);
-        } finally {
-            try {
-                client.close();
-            } catch (IOException e) {
-                log.error("Error occurred while closing http connection");
-            }
         }
     }
 
+    /**
+     * Construct error message string depending on service providers api response
+     * (I.E If unauthorized a different message will be returned)
+     *
+     * @param response of the service provider api call
+     * @return constructed error message
+     */
     private String constructErrorMessage(HttpResponse response) {
         String msg = "Error occurred while calling SP Applications API";
         if (response.getStatusLine().getStatusCode() == HttpStatus.SC_UNAUTHORIZED) {
@@ -109,8 +109,7 @@ public class WSO2IAMSPApplicationService implements ISServiceProviderApplication
         uriString += Constants.QUERY_STRING_SEPARATOR + Constants.OFFSET_QUERY_PARAM + Constants.QUERY_KEY_VALUE_SEPARATOR
                 + offset;
         req.setURI(HttpUtil.createURI(uriString));
-        CloseableHttpClient client = HttpClients.createDefault();
+        try (CloseableHttpClient client = HttpClients.createDefault()) {
-        try {
             HttpResponse response = invokeISAPI(identityServer, client, req);
             String responseBody = HttpUtil.getResponseString(response);
             if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
@@ -123,27 +122,43 @@ public class WSO2IAMSPApplicationService implements ISServiceProviderApplication
         } catch (IOException e) {
             String msg = "Error occurred while calling SP Applications API. Make sure identity server is up and running";
             log.error(msg, e);
-            throw new IdentityServerManagementException(msg);
+            throw new IdentityServerManagementException(msg, e);
-        } finally {
-            try {
-                client.close();
-            } catch (IOException e) {
-                log.error("Error occurred while closing http connection");
-            }
         }
     }
 
+    /**
+     * Takes essential prerequisite steps (I.E setting authorization header),
+     * invokes provided GET request and returns the response
+     *
+     * @param identityServer {@link IdentityServerDTO}
+     * @param client httpClient that should be used to invoke
+     * @param request GET request to be invoked
+     * @return response of the invoked api
+     */
     private HttpResponse invokeISAPI(IdentityServerDTO identityServer, HttpClient client, HttpGet request) throws IOException {
         setBasicAuthHeader(identityServer, request);
         return client.execute(request);
     }
 
+    /**
+     * Add basic auth header to provided service provider api request by getting the username and password
+     * from identity server bean
+     *
+     * @param identityServer {@link IdentityServerDTO}
+     * @param request service provider api request
+     */
     private void setBasicAuthHeader(IdentityServerDTO identityServer, HttpRequestBase request) {
         String basicAuthHeader = HttpUtil.getBasicAuthBase64Header(identityServer.getUsername(),
                 identityServer.getPassword());
         request.setHeader(HttpHeaders.AUTHORIZATION, basicAuthHeader);
     }
 
+    /**
+     * Helps to construct service provider api base url
+     *
+     * @param identityServer {@link IdentityServerDTO}
+     * @return constructed service providers api url
+     */
     private String constructAPIUrl(IdentityServerDTO identityServer) {
         String identityServerUrl = identityServer.getUrl();
         // add "/" at the end, if the server url doesn't contain "/" at the end

components/application-mgt/io.entgra.application.mgt.core/src/main/java/io/entgra/application/mgt/core/impl/ApplicationManagerImpl.java

@@ -341,6 +341,14 @@ public class ApplicationManagerImpl implements ApplicationManager {
         }
     }
 
+    /**
+     * Use to upload/save web app release artifacts (I.E icon)
+     *
+     * @param releaseDTO {@link ApplicationReleaseDTO}
+     * @param applicationArtifact {@link ApplicationArtifact}
+     * @return constructed {@link ApplicationReleaseDTO} with upload details
+     * @throws ResourceManagementException if error occurred while uploading
+     */
     private ApplicationReleaseDTO uploadWebAppReleaseArtifacts(ApplicationReleaseDTO releaseDTO, ApplicationArtifact applicationArtifact)
             throws ResourceManagementException {
         int tenantId = PrivilegedCarbonContext.getThreadLocalCarbonContext().getTenantId(true);
@@ -350,6 +358,15 @@ public class ApplicationManagerImpl implements ApplicationManager {
         return addImageArtifacts(releaseDTO, applicationArtifact, tenantId);
     }
 
+    /**
+     * Use to upload/save public app release artifacts (I.E icon)
+     *
+     * @param releaseDTO {@link ApplicationReleaseDTO}
+     * @param applicationArtifact {@link ApplicationArtifact}
+     * @param deviceType Device Type name
+     * @return constructed {@link ApplicationReleaseDTO} with upload details
+     * @throws ResourceManagementException if error occurred while uploading
+     */
     private ApplicationReleaseDTO uploadPubAppReleaseArtifacts(ApplicationReleaseDTO releaseDTO, ApplicationArtifact applicationArtifact,
                                                               String deviceType)
             throws ResourceManagementException {
@@ -384,6 +401,15 @@ public class ApplicationManagerImpl implements ApplicationManager {
         }
     }
 
+    /**
+     * Use to upload/save public app release artifacts (I.E icon)
+     *
+     * @param releaseDTO {@link ApplicationReleaseDTO}
+     * @param applicationArtifact {@link ApplicationArtifact}
+     * @param deviceType Device Type name
+     * @return constructed {@link ApplicationReleaseDTO} with upload details
+     * @throws ResourceManagementException if error occurred while uploading
+     */
     private ApplicationReleaseDTO uploadCustomAppReleaseArtifacts(ApplicationReleaseDTO releaseDTO, ApplicationArtifact applicationArtifact,
                                                                  String deviceType)
             throws ResourceManagementException, ApplicationManagementException {
@@ -402,7 +428,7 @@ public class ApplicationManagerImpl implements ApplicationManager {
         } catch (IOException e) {
             String msg = "Error occurred when uploading release artifact into the server";
             log.error(msg);
-            throw new ApplicationManagementException(msg);
+            throw new ApplicationManagementException(msg, e);
         }
         return addImageArtifacts(releaseDTO, applicationArtifact, tenantId);
     }
@@ -436,16 +462,32 @@ public class ApplicationManagerImpl implements ApplicationManager {
         }
     }
 
+    /**
+     * Helps to byte content of release binary file of application artifact
+     * This method can be useful when uploading application release binary file or when generating md5hex of release binary
+     *
+     * @param artifact {@link ApplicationArtifact}
+     * @return byte content of application release binary file
+     * @throws ApplicationManagementException if error occurred while getting byte content
+     */
     private byte[] getByteContentOfApp(ApplicationArtifact artifact) throws ApplicationManagementException{
         try {
             return IOUtils.toByteArray(artifact.getInstallerStream());
         } catch (IOException e) {
             String msg = "Error occurred while getting byte content of app binary artifact";
             log.error(msg);
-            throw new ApplicationManagementException(msg);
+            throw new ApplicationManagementException(msg, e);
         }
     }
 
+    /**
+     * Useful to generate md5hex string of application release
+     *
+     * @param applicationArtifact {@link ApplicationArtifact}
+     * @param content byte array content of application release binary file
+     * @return Generated md5hex string
+     * @throws ApplicationManagementException if any error occurred while generating md5hex string
+     */
     private String generateMD5OfApp(ApplicationArtifact applicationArtifact, byte[] content) throws ApplicationManagementException {
         try {
             String md5OfApp = StorageManagementUtil.getMD5(new ByteArrayInputStream(content));
@@ -458,7 +500,7 @@ public class ApplicationManagerImpl implements ApplicationManager {
         } catch( ApplicationStorageManagementException e) {
             String msg = "Error occurred while generating md5sum value of " + applicationArtifact.getInstallerName();
             log.error(msg);
-            throw new ApplicationManagementException(msg);
+            throw new ApplicationManagementException(msg, e);
         }
     }
 
@@ -1197,13 +1239,6 @@ public class ApplicationManagerImpl implements ApplicationManager {
         }
     }
 
-    /**
-     * Get Application and all application releases associated to the application that has given application Id
-     *
-     * @param applicationId Application Id
-     * @return {@link ApplicationDTO}
-     * @throws ApplicationManagementException if error occurred application data from the databse.
-     */
     @Override
     public ApplicationDTO getApplication(int applicationId) throws ApplicationManagementException {
         int tenantId = PrivilegedCarbonContext.getThreadLocalCarbonContext().getTenantId(true);

components/application-mgt/io.entgra.application.mgt.core/src/main/java/io/entgra/application/mgt/core/impl/SPApplicationManagerImpl.java

@@ -80,6 +80,13 @@ public class SPApplicationManagerImpl implements SPApplicationManager {
         return APIUtil.identityServerDtoToIdentityServerResponse(identityServerDTO);
     }
 
+    /**
+     * This is similar to getIdentityServerFromDB method except throws {@link NotFoundException} if identity server
+     * does not exist for the given id
+     *
+     * @param identityServerId id of identity server
+     * @return {@link IdentityServerDTO}
+     */
     private IdentityServerDTO getIdentityServer(int identityServerId) throws ApplicationManagementException {
         IdentityServerDTO identityServerDTO = getIdentityServerFromDB(identityServerId);
         if (identityServerDTO == null) {
@@ -90,6 +97,12 @@ public class SPApplicationManagerImpl implements SPApplicationManager {
         return identityServerDTO;
     }
 
+    /**
+     * Use to get {@link IdentityServerDTO} bean from database. Returns null if does not exist
+     *
+     * @param identityServerId id of identity server
+     * @return {@link IdentityServerDTO}
+     */
     private IdentityServerDTO getIdentityServerFromDB(int identityServerId) throws ApplicationManagementException {
         int tenantId = PrivilegedCarbonContext.getThreadLocalCarbonContext().getTenantId();
         try {
@@ -191,6 +204,12 @@ public class SPApplicationManagerImpl implements SPApplicationManager {
         }
     }
 
+    /**
+     * Validate the identity server delete request
+     *
+     * @param identityServerId identity server id
+     * @throws BadRequestException if provided identity server id is invalid
+     */
     private void validateIdentityServerDeleteRequest(int identityServerId) throws ApplicationManagementException {
         IdentityServerDTO identityServerDTO = getIdentityServerFromDB(identityServerId);
         if (identityServerDTO == null) {
@@ -200,6 +219,15 @@ public class SPApplicationManagerImpl implements SPApplicationManager {
         }
     }
 
+    /**
+     * This method is useful to re-construct the api params Map using updated identity server bean {@link IdentityServerDTO}
+     * For example updated identity server bean may contain only updated api param, in which case the existing api param values
+     * should be re-added to updated identity server bean
+     *
+     * @param updatedIdentityServerDTO updated identity server request payload
+     * @param existingIdentityServerDTO corresponding existing identity server of updated identity server
+     * @return Constructed api param map
+     */
     private Map<String, String> constructUpdatedApiParams(IdentityServerDTO updatedIdentityServerDTO,
                                                           IdentityServerDTO existingIdentityServerDTO) {
         Map<String, String> updatedApiParams = updatedIdentityServerDTO.getApiParams();
@@ -292,6 +320,12 @@ public class SPApplicationManagerImpl implements SPApplicationManager {
         validateIdentityServerUrl(identityServerDTO.getUrl());
     }
 
+    /**
+     * Validate provided identity server url (For example make sure it uses http/https protocol)
+     *
+     * @param url url of the identity server
+     * @throws BadRequestException if url is invalid
+     */
     private void validateIdentityServerUrl(String url) throws BadRequestException {
         String[] schemes = {"http","https"};
         UrlValidator urlValidator = new UrlValidator(schemes, UrlValidator.ALLOW_LOCAL_URLS);
@@ -302,17 +336,32 @@ public class SPApplicationManagerImpl implements SPApplicationManager {
         }
     }
 
-    private void validateUpdateIdentityServerRequestApiParam(IdentityServerDTO identityServerUpdateDTO,
+    /**
+     * Validate provided api params map in a identity server updated request
+     * For example the updated api param map may not contain all the required api params
+     *
+     * @param updatedIdentityServerDto  Identity server update request payload bean
+     * @param existingIdentityServerDTO Corresponding existing identity server bean of the updated identity server
+     * @throws ApplicationManagementException if any api param is invalid
+     */
+    private void validateUpdateIdentityServerRequestApiParam(IdentityServerDTO updatedIdentityServerDto,
                                                              IdentityServerDTO existingIdentityServerDTO) throws ApplicationManagementException {
         ISServiceProviderApplicationService serviceProviderApplicationService =
                 ISServiceProviderApplicationService.of(existingIdentityServerDTO.getProviderName());
         List<String> requiredApiParams = serviceProviderApplicationService.getRequiredApiParams();
-        if (!identityServerUpdateDTO.getProviderName().equals(existingIdentityServerDTO.getProviderName())) {
+        if (!updatedIdentityServerDto.getProviderName().equals(existingIdentityServerDTO.getProviderName())) {
-            validateAllRequiredParamsExists(identityServerUpdateDTO, requiredApiParams);
+            validateAllRequiredParamsExists(updatedIdentityServerDto, requiredApiParams);
         }
-        validateIfAnyInvalidParamExists(identityServerUpdateDTO, requiredApiParams);
+        validateIfAnyInvalidParamExists(updatedIdentityServerDto, requiredApiParams);
     }
 
+    /**
+     * Validate api params map of identity server create request payload
+     * For example the api param map may not contain all the required api params
+     *
+     * @param identityServerDTO {@link IdentityServerDTO}
+     * @throws ApplicationManagementException if any api param is invalid
+     */
     private void validateCreateIdentityServerRequestApiParams(IdentityServerDTO identityServerDTO) throws ApplicationManagementException {
         ISServiceProviderApplicationService serviceProviderApplicationService =
                 ISServiceProviderApplicationService.of(identityServerDTO.getProviderName());
@@ -321,6 +370,13 @@ public class SPApplicationManagerImpl implements SPApplicationManager {
         validateIfAnyInvalidParamExists(identityServerDTO, requiredApiParams);
     }
 
+    /**
+     * Make sure if all required api params exists for the given identity server bean
+     *
+     * @param identityServerDTO {@link IdentityServerDTO}
+     * @param requiredApiParams all mandatory api params
+     * @throws BadRequestException if a required api param does not exist
+     */
     private void validateAllRequiredParamsExists(IdentityServerDTO identityServerDTO, List<String> requiredApiParams)
             throws BadRequestException {
         for (String param : requiredApiParams) {
@@ -333,6 +389,14 @@ public class SPApplicationManagerImpl implements SPApplicationManager {
         }
     }
 
+    /**
+     * Make sure if all api params are valid
+     * For example it may contain an unwanted api param
+     *
+     * @param identityServerDTO {@link IdentityServerDTO}
+     * @param requiredApiParams all required api params
+     * @throws BadRequestException if an unwanted api param exist
+     */
     private void validateIfAnyInvalidParamExists(IdentityServerDTO identityServerDTO, List<String> requiredApiParams)
             throws BadRequestException {
         for (String param : identityServerDTO.getApiParamKeys()) {
@@ -344,6 +408,12 @@ public class SPApplicationManagerImpl implements SPApplicationManager {
         }
     }
 
+    /**
+     * If the given providerName does not exist in the identity server config file
+     *
+     * @param providerName Name of the identity service provider
+     * @return if provider name exist in identity server config
+     */
     private boolean isIdentityServiceProviderNotConfigured(String providerName) {
         List<IdentityServiceProvider> identityServiceProviders = ConfigurationManager.getInstance().getIdentityServerConfiguration().
                 getIdentityServiceProviders();
@@ -508,7 +578,7 @@ public class SPApplicationManagerImpl implements SPApplicationManager {
             } catch (ApplicationManagementException e) {
                 String msg = "Identity service provider configuration file is invalid. Hence failed to proceed.";
                 log.error(msg);
-                throw new ApplicationManagementException(msg);
+                throw new ApplicationManagementException(msg, e);
             }
         }
         return identityServiceProviderDTOS;

components/application-mgt/io.entgra.application.mgt.publisher.api/src/main/java/io/entgra/application/mgt/publisher/api/services/impl/SPApplicationServiceImpl.java

@@ -95,7 +95,7 @@ public class SPApplicationServiceImpl implements SPApplicationService {
             return Response.status(Response.Status.OK).entity("Successfully deleted identity server").build();
         } catch (NotFoundException e) {
             String msg = "Identity server with the id " + id + " does not exist.";
-            log.error(msg);
+            log.error(msg, e);
             return Response.status(Response.Status.BAD_REQUEST).entity(msg).build();
         } catch (ApplicationManagementException e) {
             String errMsg = "Error occurred while trying to merge identity server apps with existing apps";
@@ -114,7 +114,7 @@ public class SPApplicationServiceImpl implements SPApplicationService {
             return Response.status(Response.Status.OK).entity(identityServer).build();
         } catch (NotFoundException e) {
             String msg = "Identity server with the id " + id + " does not exist.";
-            log.error(msg);
+            log.error(msg, e);
             return Response.status(Response.Status.BAD_REQUEST).entity(msg).build();
         } catch (ApplicationManagementException e) {
             String errMsg = "Error occurred while trying to merge identity server apps with existing apps";
@@ -133,7 +133,7 @@ public class SPApplicationServiceImpl implements SPApplicationService {
             return Response.status(Response.Status.OK).entity(identityServerResponse).build();
         } catch (NotFoundException e) {
             String msg = "Identity server with the id " + id + " does not exist.";
-            log.error(msg);
+            log.error(msg, e);
             return Response.status(Response.Status.BAD_REQUEST).entity(msg).build();
         } catch (BadRequestException e) {
             String errMsg = "Identity server request payload is invalid";

components/device-mgt/org.wso2.carbon.device.mgt.core/src/main/java/org/wso2/carbon/device/mgt/core/common/util/FileUtil.java

@@ -24,6 +24,12 @@ import java.util.Base64;
 
 public class FileUtil {
 
+    /**
+     * Useful to remove path separator string "," from base64 string
+     *
+     * @param base64String base64 string
+     * @return base64 string without path separator
+     */
     public static String removePathSeparatorFromBase64String(String base64String) {
         String partSeparator = ",";
         if (base64String.contains(partSeparator)) {
@@ -32,6 +38,12 @@ public class FileUtil {
         return base64String;
     }
 
+    /**
+     * Useful to convert base64 string to input stream
+     *
+     * @param base64 base64 string to be converted
+     * @return {@link InputStream} of the provided base64 string
+     */
     public static InputStream base64ToInputStream(String base64) {
         base64 = FileUtil.removePathSeparatorFromBase64String(base64);
         byte[] base64Bytes = Base64.getDecoder().decode(base64);
@@ -72,13 +84,24 @@ public class FileUtil {
         return suffix;
     }
 
+    /**
+     * Use to extract file extension from file name
+     *
+     * @param fileName name of the file
+     * @return extension of the file
+     */
     private static String extractFileExtension(String fileName) {
         return fileName.substring(fileName.lastIndexOf('.') + 1);
     }
 
+    /**
+     * Use to extract the file name without the extension
+     * For example if you provide "main.java" as the fileName this will return main
+     *
+     * @param fileName name of the file
+     * @return file name without file extension
+     */
     private static String extractFileNameWithoutExtension(String fileName) {
         return fileName.substring(0, fileName.lastIndexOf('.'));
     }
-
-
 }

components/device-mgt/org.wso2.carbon.device.mgt.core/src/main/java/org/wso2/carbon/device/mgt/core/common/util/HttpUtil.java

@@ -32,20 +32,47 @@ import java.util.Map;
 
 public class HttpUtil {
 
+    /**
+     * Use to create {@link URI} from string
+     * This does encoding of the provided uri string before creating the URI
+     *
+     * @param uriString uri string to be used to create the URI
+     * @return created URI
+     */
     public static URI createURI(String uriString) {
         uriString = uriString.replace(" ", "%20");
         return URI.create(uriString);
     }
 
+    /**
+     * Use to create basic auth header string for provided credentials
+     *
+     * @param userName username credential
+     * @param password password credential
+     * @return Basic auth header
+     */
     public static String getBasicAuthBase64Header(String userName, String password) {
         return Constants.BASIC_AUTH_HEADER_PREFIX + getBase64Encode(userName, password);
     }
 
+    /**
+     * Use to get the base64 encoded string of key value pair.
+     * For example this can be useful when creating basic auth header
+     *
+     * @return base64 encoded string of provided key and value
+     */
     public static String getBase64Encode(String key, String value) {
         return new String(Base64.encodeBase64((key + ":" + value).getBytes()));
     }
 
-    public static String getRequestSubPathFromEnd(URI requestUri, int position) {
+    /**
+     * Useful to get the sub path in a position from the given uri starting from end of the uri
+     *
+     * @param requestUri {@link URI}
+     * @param position of which the sub path is needed
+     * @return Sub path of the uri
+     */
+    public static String extractRequestSubPathFromEnd(URI requestUri, int position) {
         if (requestUri.getPath() != null) {
             String[] pathList = requestUri.getPath().split("/");
             if (pathList.length - 1 >= position) {
@@ -55,8 +82,15 @@ public class HttpUtil {
         return null;
     }
 
-    public static String getRequestSubPath(String fullPath, int position) {
+    /**
-        String[] pathList = fullPath.split("/");
+     * Useful to get the sub path in a position from the given uri
+     *
+     * @param uri uri string from which the sub path should be extracted
+     * @param position of which the sub path is needed
+     * @return Sub path of the uri
+     */
+    public static String extractRequestSubPath(String uri, int position) {
+        String[] pathList = uri.split("/");
         if (pathList.length - 1 > position) {
             String path = pathList[position + 1];
             if(path.contains(Constants.URI_QUERY_SEPARATOR)) {
@@ -67,14 +101,37 @@ public class HttpUtil {
         return null;
     }
 
+    /**
+     * This returns the response body as string
+     *
+     * @param response {@link HttpResponse}
+     * @return Response body string
+     * @throws IOException if errors while converting response body to string
+     */
     public static String getResponseString(HttpResponse response) throws IOException {
         return EntityUtils.toString(response.getEntity());
     }
 
-    public static boolean isQueryParamExist(String param, URI request) {
+    /**
-        Map<String, List<String>> queryMap = getQueryMap(request);
+     * Useful to check if a given query param exists in uri
+     *
+     * @param param query param to be checked
+     * @param uri in which query param should be checked
+     * @return if the provided query parameter exists in uri
+     */
+    public static boolean isQueryParamExist(String param, URI uri) {
+        Map<String, List<String>> queryMap = getQueryMap(uri);
         return queryMap.containsKey(param);
     }
+
+    /**
+     * This is useful to get first query parameter value from a query map.
+     * For example a query parameter may have multiple values.
+     *
+     * @param param query parameter of which the value is needed
+     * @param queryMap query map which contains query paramters and it's values
+     * @return First value of provided query parameter
+     */
     public static String getFirstQueryValue(String param, Map<String, List<String>> queryMap) {
         List<String> valueList = queryMap.get(param);
         String firstValue = null;
@@ -83,6 +140,20 @@ public class HttpUtil {
         }
         return firstValue;
     }
+
+    /**
+     * This constructs a key/value Map from query string of the provided uri.
+     * In other words this will create a map with query parameters as keys and their
+     * values as values.
+     *
+     * For example if the uri contains "?bar=1&foo=2" this will return a map
+     * with bar and foo as keys and 1 and 2 as their values
+     *
+     * This is similar to getQueryMap(URI uri) method except that this accepts uri string
+     *
+     * @param uri of which the query map to be created
+     * @return Query map of the provided uri
+     */
     public static Map<String, List<String>> getQueryMap(String uri) {
         String query = getQueryFromURIPath(uri);
         Map<String, List<String>> map = new HashMap<>();
@@ -103,8 +174,20 @@ public class HttpUtil {
         }
         return map;
     }
-    public static Map<String, List<String>> getQueryMap(URI request) {
+
-        String query = request.getQuery();
+    /**
+     * This constructs a key/value Map from query string of the provided uri.
+     * In other words this will create a map with query parameters as keys and their
+     * values as values.
+     *
+     * For example if the uri contains "?bar=1&foo=2" this will return a map
+     * with bar and foo as keys and 1 and 2 as their values
+     *
+     * @param uri of which the query map to be created
+     * @return Query map of the provided uri
+     */
+    public static Map<String, List<String>> getQueryMap(URI uri) {
+        String query = uri.getQuery();
         Map<String, List<String>> map = new HashMap<>();
         if (query != null) {
             String[] params = query.split("&");
@@ -123,6 +206,13 @@ public class HttpUtil {
         }
         return map;
     }
+
+    /**
+     * Get query string from uri path. Return null if no query string exists
+     *
+     * @param uri of which query string should be taken
+     * @return Query string of the provided uri
+     */
     public static String getQueryFromURIPath(String uri) {
         String query = null;
         if (uri.length() > "?".length() && uri.contains("?")) {
@@ -134,6 +224,12 @@ public class HttpUtil {
         return query;
     }
 
+    /**
+     * Get content type of http response
+     *
+     * @param response {@link HttpResponse}
+     * @return Content type
+     */
     public static String getContentType(HttpResponse response) {
         ContentType contentType = ContentType.getOrDefault(response.getEntity());
         return contentType.getMimeType();