code: private String makeSignature(List<ASTType> paramTypes) {
          StringBuilder builder = new StringBuilder();
          builder.append('(');
          for (ASTType paramType : paramTypes) {
              makeTypeDescriptor(builder, paramType);
          }
  
          builder.append(')');
          return builder.toString();
      }
docs: Makes a descriptor for a given method.
  
  @param paramTypes  parameter types.
  @return method descriptor