@Override
  public String toString() {
    return "Index ["
        + " Name=" + getName()
        + " Type =" + getType()
        + " IdxExp=" + getIndexedExpression()
        + " From=" + getFromClause()
        + " Proj=" + getProjectionAttributes()
        + ']';
  }
This implementation is for PrimaryKeyIndex. RangeIndex has its own implementation. For
PrimaryKeyIndex , this method should not be used
<p>
TODO: check if an Exception should be thrown if the function implementation of this class gets
invoked
geode-core/src/main/java/org/apache/geode/cache/query/internal/index/AbstractIndex.java