code: @Nullable
      public static XMethod getXMethod(final XClass xClass, final String methodName, final String methodSig) {
          if (xClass == null) {
              return null;
          }
  
          XMethod xMethod = xClass.findMethod(methodName, methodSig, false);
          if (xMethod == null) {
              ClassDescriptor descriptor = xClass.getSuperclassDescriptor();
              if (descriptor != null) {
                  final XClass superClass = getXClass(descriptor);
                  xMethod = getXMethod(superClass, methodName, methodSig);
              }
          }
          return xMethod;
      }
docs: Looks for the method up the class hierarchy.
  
  @param xClass
  the class where to look for the method
  @param methodName
  the name of the method to look for
  @param methodSig
  the signature of the method to look for
  @return the method