fix sonar finding (#2592)

* fix sonar finding

first only the found smell
https://sonarcloud.io/project/issues?impactSeverities=HIGH&resolved=false&sinceLeakPeriod=true&types=CODE_SMELL&id=cloudfoundry-identity-parent

later also implemented recommendations from sonar linter

* check null

server/src/main/java/org/cloudfoundry/identity/uaa/zone/MultitenantJdbcClientDetailsService.java

@@ -89,7 +89,7 @@ public class MultitenantJdbcClientDetailsService extends MultitenantClientServic
             "update oauth_client_details set ";
 
     private static final String DEFAULT_UPDATE_STATEMENT =
-            BASE_UPDATE_STATEMENT + CLIENT_FIELDS_FOR_UPDATE.replaceAll(", ", "=?, ")
+            BASE_UPDATE_STATEMENT + CLIENT_FIELDS_FOR_UPDATE.replace(", ", "=?, ")
                     + "=? where client_id = ? and identity_zone_id = ?";
 
     private static final String DEFAULT_UPDATE_SECRET_STATEMENT =
@@ -103,6 +103,7 @@ public class MultitenantJdbcClientDetailsService extends MultitenantClientServic
 
     private static final String DELETE_CLIENTS_BY_ZONE =
             "delete from oauth_client_details where identity_zone_id = ?";
+    private static final String NO_CLIENT_FOUND_WITH_ID = "No client found with id = ";
 
     private RowMapper<ClientDetails> rowMapper = new ClientDetailsRowMapper();
 
@@ -147,33 +148,30 @@ public void addClientDetails(ClientDetails clientDetails, String zoneId) throws
 
     private boolean exists(String clientId, String zoneId) {
         List<String> idResults = jdbcTemplate.queryForList(SINGLE_SELECT_STATEMENT, String.class, clientId, zoneId);
-        if (idResults != null && idResults.size() == 1) {
-            return true;
-        }
-        return false;
+        return idResults != null && idResults.size() == 1;
     }
 
     @Override
     public void updateClientDetails(ClientDetails clientDetails, String zoneId) throws NoSuchClientException {
         int count = jdbcTemplate.update(DEFAULT_UPDATE_STATEMENT, getFieldsForUpdate(clientDetails, zoneId));
         if (count != 1) {
-            throw new NoSuchClientException("No client found with id = " + clientDetails.getClientId() + " in identity zone id=" + zoneId);
+            throw new NoSuchClientException(NO_CLIENT_FOUND_WITH_ID + clientDetails.getClientId() + " in identity zone id=" + zoneId);
         }
     }
 
     @Override
     public void updateClientSecret(String clientId, String secret, String zoneId) throws NoSuchClientException {
         int count = jdbcTemplate.update(DEFAULT_UPDATE_SECRET_STATEMENT, secret != null ? passwordEncoder.encode(secret) : null, clientId, zoneId);
         if (count != 1) {
-            throw new NoSuchClientException("No client found with id = " + clientId);
+            throw new NoSuchClientException(NO_CLIENT_FOUND_WITH_ID + clientId);
         }
     }
 
     @Override
     public void updateClientJwtConfig(String clientId, String keyConfig, String zoneId) throws NoSuchClientException {
         int count = jdbcTemplate.update(DEFAULT_UPDATE_CLIENT_JWT_CONFIG_STATEMENT, keyConfig, clientId, zoneId);
         if (count != 1) {
-            throw new NoSuchClientException("No client found with id = " + clientId);
+            throw new NoSuchClientException(NO_CLIENT_FOUND_WITH_ID + clientId);
         }
     }
 
@@ -201,7 +199,7 @@ private Object[] getInsertClientDetailsFields(ClientDetails clientDetails, Strin
 
     private Object[] getFieldsForUpdate(ClientDetails clientDetails, String zoneId) {
 
-        Map<String, Object> additionalInformation = new HashMap(clientDetails.getAdditionalInformation());
+        Map<String, Object> additionalInformation = new HashMap<>(clientDetails.getAdditionalInformation());
         Collection<String> requiredGroups = (Collection<String>) additionalInformation.remove(REQUIRED_USER_GROUPS);
 
         String json;
@@ -242,7 +240,7 @@ private String getAutoApproveScopes(ClientDetails clientDetails) {
         if (clientDetails.isAutoApprove("true")) {
             return "true"; // all scopes autoapproved
         }
-        Set<String> scopes = new HashSet<String>();
+        Set<String> scopes = new HashSet<>();
         for (String scope : clientDetails.getScope()) {
             if (clientDetails.isAutoApprove(scope)) {
                 scopes.add(scope);
@@ -260,7 +258,7 @@ public int deleteByIdentityZone(String zoneId) {
     public int deleteByClient(String clientId, String zoneId) {
         int count = jdbcTemplate.update(DEFAULT_DELETE_STATEMENT, clientId, zoneId);
         if (count == 0) {
-            throw new NoSuchClientException("No client found with id = " + clientId);
+            throw new NoSuchClientException(NO_CLIENT_FOUND_WITH_ID + clientId);
         }
         return count;
     }
@@ -279,7 +277,7 @@ public void addClientSecret(String clientId, String newSecret, String zoneId) th
                 .append(encodedNewSecret);
         int count = jdbcTemplate.update(DEFAULT_UPDATE_SECRET_STATEMENT, newSecretBuilder.toString(), clientId, zoneId);
         if (count != 1) {
-            throw new NoSuchClientException("No client found with id = " + clientId);
+            throw new NoSuchClientException(NO_CLIENT_FOUND_WITH_ID + clientId);
         }
     }
 
@@ -385,7 +383,7 @@ public ClientDetails mapRow(ResultSet rs, int rowNum) throws SQLException {
 
             //required_user_groups
             String requiredUserGroups = rs.getString(14);
-            if (StringUtils.isEmpty(requiredUserGroups)) {
+            if (!StringUtils.hasLength(requiredUserGroups)) {
                 details.addAdditionalInformation(REQUIRED_USER_GROUPS, emptySet());
             } else {
                 details.addAdditionalInformation(REQUIRED_USER_GROUPS, commaDelimitedListToSet(requiredUserGroups));