code: int getMethodIndex(ExecutableElement method)
      {
          TypeElement declaringClass = (TypeElement) method.getEnclosingElement();
          String fullyQualifiedname = declaringClass.getQualifiedName().toString();
          return getRefIndex(Methodref.class, fullyQualifiedname, method.getSimpleName().toString(), Descriptor.getDesriptor(method));
      }
docs: Returns the constant map index to method
  @param method
  @return