public int[] getMapping() {
    return mapping;
  }
An int array of size equal to the number of Iterators present in the Group representing the
Iterators for that region. It identifies the index result field position which maps to the
RuntimeIterator for the Group. The mapping of index result field is 1 based ( not zero). For
example the second Iterator of the group ( 0 indxe based , hence 1 ) will map to the field
position in the Index Result given by the value maping[1]. If an iterator has no mapping , the
value will be 0. *
geode-core/src/main/java/org/apache/geode/cache/query/internal/index/IndexData.java