Fix possible NPE when media type is not specified

Content type is automatically generated from the Http client hence removing

components/ui-request-interceptor/io.entgra.ui.request.interceptor/src/main/java/io/entgra/ui/request/interceptor/InvokerHandler.java

@@ -205,8 +205,7 @@ public class InvokerHandler extends HttpServlet {
                     entityBuilder.addPart(item.getFieldName(), new InputStreamBody(item.getInputStream(),
                             ContentType.create(item.getContentType()), item.getName()));
                 } else {
-                    entityBuilder.addTextBody(item.getFieldName(), item.getString(),
+                    entityBuilder.addTextBody(item.getFieldName(), item.getString());
-                            ContentType.create(item.getContentType()));
                 }
             }
             proxyRequest.setEntity(entityBuilder.build());