code: private static MethodNode findDefaultMethodFromInterface(final ClassNode cNode, final String name, final Parameter[] params) {
          if (cNode == null) {
              return null;
          }
          if (cNode.isInterface()) {
              MethodNode method = cNode.getMethod(name, params);
              if (method!=null && !method.isAbstract()) {
                  // this is a Java 8 only behavior!
                  return method;
              }
          }
          ClassNode[] interfaces = cNode.getInterfaces();
          for (ClassNode anInterface : interfaces) {
              MethodNode res = findDefaultMethodFromInterface(anInterface, name, params);
              if (res!=null) {
                  return res;
              }
          }
          return findDefaultMethodFromInterface(cNode.getSuperClass(), name, params);
      }
docs: An utility method which tries to find a method with default implementation (in the Java 8 semantics).
  @param cNode a class node
  @param name the name of the method
  @param params the parameters of the method
  @return a method node corresponding to a default method if it exists