diff --git a/src/main/java/eu/dnetlib/repo/manager/service/RepositoryServiceImpl.java b/src/main/java/eu/dnetlib/repo/manager/service/RepositoryServiceImpl.java
index 8aee836..3cdf396 100644
--- a/src/main/java/eu/dnetlib/repo/manager/service/RepositoryServiceImpl.java
+++ b/src/main/java/eu/dnetlib/repo/manager/service/RepositoryServiceImpl.java
@@ -205,13 +205,11 @@ public class RepositoryServiceImpl implements RepositoryService {
 
         for (String repoId : ids) {
             requestFilter.setId(repoId);
-
             DatasourceResponse rs = restTemplate.postForObject(uriComponents.toUri(), requestFilter, DatasourceResponse.class);
-            if (rs == null) {
+            if ( rs == null )
                 logger.error("The \"DatasourceResponse\" is null!");
-            } else {
+            else
                 datasourceDetailsList.addAll(rs.getDatasourceInfo());
-            }
         }
 
         resultSet = objectMapper.readValue(objectMapper.writeValueAsString(datasourceDetailsList),
@@ -547,13 +545,12 @@ public class RepositoryServiceImpl implements RepositoryService {
                                                       RepositoryInterface repositoryInterface,
                                                       String desiredCompatibilityLevel) throws Exception {
         Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
-        Repository e = this.getRepositoryById(repoId);
-        repositoryInterface = fillInterfaceFields(e, repositoryInterface, datatype);
+        Repository repo = this.getRepositoryById(repoId);
+        repositoryInterface = fillInterfaceFields(repo, repositoryInterface, datatype);
 
         UriComponents uriComponents = UriComponentsBuilder
                 .fromHttpUrl(baseAddress + "/ds/api/add/")
-                .build()
-                .encode();
+                .build().encode();
 
         HttpEntity<RepositoryInterface> httpEntity = new HttpEntity<>(repositoryInterface, httpHeaders);
         restTemplate.postForObject(uriComponents.toUri(), httpEntity, String.class);
@@ -561,15 +558,17 @@ public class RepositoryServiceImpl implements RepositoryService {
         // Explicitly update validation set (updating the interface does not allow updating the set value)
         this.updateValidationSet(repoId, repositoryInterface.getId(), repositoryInterface.getAccessSet());
 
-        emailUtils.sendAdminRegisterInterfaceEmail(e, comment, repositoryInterface, desiredCompatibilityLevel, authentication);
-        emailUtils.sendUserRegisterInterfaceEmail(e, comment, repositoryInterface, desiredCompatibilityLevel, authentication);
+        emailUtils.sendAdminRegisterInterfaceEmail(repo, comment, repositoryInterface, desiredCompatibilityLevel, authentication);
+        emailUtils.sendUserRegisterInterfaceEmail(repo, comment, repositoryInterface, desiredCompatibilityLevel, authentication);
 
-        if (desiredCompatibilityLevel != null && (repositoryInterface.getCompatibility() == null || !repositoryInterface.getCompatibility().equals(desiredCompatibilityLevel))) {
+        String prevCompatibilityLevel = repositoryInterface.getCompatibility();
+        if ( (desiredCompatibilityLevel != null)
+                && ((prevCompatibilityLevel == null) || ! prevCompatibilityLevel.equals(desiredCompatibilityLevel))) {
             InterfaceComplianceRequest request = new InterfaceComplianceRequest(repoId, repositoryInterface.getId(), desiredCompatibilityLevel);
             interfaceComplianceService.create(request);
         }
 
-        submitInterfaceValidation(e, getAuthenticatedUser().getEmail(), repositoryInterface, false, repositoryInterface.getCompatibility());
+        submitInterfaceValidation(repo, getAuthenticatedUser().getEmail(), repositoryInterface, false, desiredCompatibilityLevel);
 
         return repositoryInterface;
     }
diff --git a/src/main/java/eu/dnetlib/repo/manager/service/aai/registry/RegistryCalls.java b/src/main/java/eu/dnetlib/repo/manager/service/aai/registry/RegistryCalls.java
index dc7c5f1..be987bb 100644
--- a/src/main/java/eu/dnetlib/repo/manager/service/aai/registry/RegistryCalls.java
+++ b/src/main/java/eu/dnetlib/repo/manager/service/aai/registry/RegistryCalls.java
@@ -16,7 +16,6 @@ import org.springframework.beans.factory.annotation.Value;
 import org.springframework.security.core.context.SecurityContextHolder;
 import org.springframework.stereotype.Service;
 
-import javax.validation.constraints.NotNull;
 import java.io.UnsupportedEncodingException;
 import java.net.URLEncoder;
 import java.util.ArrayList;
diff --git a/src/main/java/eu/dnetlib/repo/manager/utils/Converter.java b/src/main/java/eu/dnetlib/repo/manager/utils/Converter.java
index 3dccc4e..b250602 100644
--- a/src/main/java/eu/dnetlib/repo/manager/utils/Converter.java
+++ b/src/main/java/eu/dnetlib/repo/manager/utils/Converter.java
@@ -6,7 +6,6 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.io.BufferedReader;
-import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.util.ArrayList;
 import java.util.List;
@@ -22,13 +21,11 @@ public class Converter {
     public static List<String> readFile(String filename) {
         String line;
         List<String> list = new ArrayList<>();
-        try {
-            InputStream in = Converter.class.getResourceAsStream("/eu/**/" + filename);
-            BufferedReader br = new BufferedReader(new InputStreamReader(in));  // It may throw an NPE.
+        try ( BufferedReader br = new BufferedReader(new InputStreamReader(Objects.requireNonNull(Converter.class.getResourceAsStream("/eu/**/" + filename)))) )
+        {
             while ((line = br.readLine()) != null) {
                 list.add(line.trim());
             }
-            br.close();
         } catch (Exception e) {
             logger.error("Error opening file!", e);
         }