function concatJsonPointer(traceFromParent, targetInRoot) {
  const traceFromParentAsString = traceFromParent.join(jsonPointerLevelSeparator);
  return localPointer + targetInRoot + jsonPointerLevelSeparator + traceFromParentAsString;
}
concats the inputs to generate the json pointer
@constructor
@param {string} traceFromParent the trace from parent.
@param {string} targetInRoot - The root element where we will point
@returns {string} - the concatenated json pointer