private void prepareProjectionAttributes(String projectionAttributes)
      throws IndexInvalidException {
    if (projectionAttributes != null && !projectionAttributes.equals("*")) {
      throw new IndexInvalidException(
          String.format("Invalid projection attributes : ' %s '",
              projectionAttributes));
    }
    this.projectionAttributes = projectionAttributes;
  }
This function is modified so that if the indexed expression has any dependency on the 0th
iterator, then it needs to modified by using the missing link so that it is derivable from the
0th iterator.
<p>
TODO: refactor large method prepareIndexExpression
geode-core/src/main/java/org/apache/geode/cache/query/internal/index/FunctionalIndexCreationHelper.java