code: public static String toExtensionId(String groupId, String artifactId, String classifier)
      {
          StringBuilder builder = new StringBuilder();
  
          builder.append(groupId);
          builder.append(':');
          builder.append(artifactId);
          if (StringUtils.isNotEmpty(classifier)) {
              builder.append(':');
              builder.append(classifier);
          }
  
          return builder.toString();
      }
docs: Create a extension identifier from Maven artifact identifier elements.
  
  @param groupId the group id
  @param artifactId the artifact id
  @param classifier the classifier
  @return the extension identifier