code: static long computeMsgIdUsingBracedPhs(
        ImmutableList<SoyMsgPart> msgParts, @Nullable String meaning, @Nullable String contentType) {
      return computeMsgIdHelper(msgParts, true, meaning, contentType);
    }
docs: Computes an alternate unique message id for a message, given the message parts, the meaning
  string (if any), and the content type (if any). These are the only elements incorporated into
  the message id.
  
  <p>In particular, note that the id of a message does not change when its desc changes.
  
  <p>Important: This is an alternate message id computation using braced placeholders. Only use
  this function instead of {@link #computeMsgId} if you know that you need this alternate format.
  
  @param msgParts The parts of the message.
  @param meaning The meaning string, or null if none (usually null).
  @param contentType Content type of the document that this message will appear in (e.g. "{@code
  text/html}", or null if not used..
  @return The computed message id.