code: public static String ceylonModuleBaseName(final String groupId, final String artifactId) {
          if (groupId == null || artifactId == null || "".equals(artifactId) || artifactId.contains(".")) {
              throw new IllegalArgumentException(" Null or empty, or '.' is not allowed in artifactId");
          }
          return groupId + GROUP_SEPARATOR +  artifactId;
      }
docs: Determines the Ceylon module name (without extension).
  
  @param groupId Maven group id
  @param artifactId Maven artifact id
  @return String The module base name