code: private void extractMessageFrom(
        Builder builder, Node valueNode, Node docNode)
        throws MalformedException {
      maybeInitMetaDataFromJsDoc(builder, docNode);
      extractFromCallNode(builder, valueNode);
    }
docs: Creates a {@link JsMessage} for a JS message defined using an assignment to
  a qualified name (e.g <code>a.b.MSG_X = goog.getMsg(...);</code>).
  
  @param builder the message builder
  @param valueNode a node in a JS message value
  @param docNode the node containing the jsdoc.
  @throws MalformedException if {@code getPropNode} does not
  correspond to a valid JS message node