Improve check revision deployment list length logic

components/apimgt-extensions/io.entgra.device.mgt.core.apimgt.webapp.publisher/src/main/java/io/entgra/device/mgt/core/apimgt/webapp/publisher/APIPublisherServiceImpl.java

@@ -314,23 +314,28 @@ public class APIPublisherServiceImpl implements APIPublisherService {
                                     }
                                 }
 
-                                // This will retrieve the deployed revision
-                                JSONArray revisionDeploymentList = (JSONArray) publisherRESTAPIServices.getAPIRevisions(apiApplicationKey,
-                                        accessTokenInfo, existingAPI.getString("id"), true).get("list");
-                                // This will retrieve the un deployed revision list
-                                JSONArray undeployedRevisionList = (JSONArray) publisherRESTAPIServices.getAPIRevisions(apiApplicationKey,
-                                        accessTokenInfo, existingAPI.getString("id"), false).get("list");
                                 int apiRevisionCount = (int) publisherRESTAPIServices.getAPIRevisions(apiApplicationKey,
                                         accessTokenInfo, existingAPI.getString("id"), null).get("count");
-
                                 if (apiRevisionCount >= 5) {
+                                    // This will retrieve the deployed revision
+                                    JSONArray revisionDeploymentList = (JSONArray) publisherRESTAPIServices.getAPIRevisions(
+                                            apiApplicationKey, accessTokenInfo, existingAPI.getString("id"),
+                                            true).get("list");
+                                    if (revisionDeploymentList.length() > 0) {
                                         JSONObject latestRevisionDeployment = revisionDeploymentList.getJSONObject(0);
-                                    JSONObject earliestUndeployRevision = undeployedRevisionList.getJSONObject(0);
                                         publisherRESTAPIServices.undeployAPIRevisionDeployment(apiApplicationKey,
                                                 accessTokenInfo, latestRevisionDeployment, existingAPI.getString("id"));
+                                    }
+                                    // This will retrieve the un deployed revision list
+                                    JSONArray undeployedRevisionList = (JSONArray) publisherRESTAPIServices.getAPIRevisions(
+                                            apiApplicationKey, accessTokenInfo, existingAPI.getString("id"),
+                                            false).get("list");
+                                    if (undeployedRevisionList.length() > 0) {
+                                        JSONObject earliestUndeployRevision = undeployedRevisionList.getJSONObject(0);
                                         publisherRESTAPIServices.deleteAPIRevision(apiApplicationKey, accessTokenInfo,
                                                 earliestUndeployRevision, existingAPI.getString("id"));
                                     }
+                                }
 
                                 // create new revision
                                 APIRevision apiRevision = new APIRevision();