@Override
  public void setElementType(ObjectType elementType) {
    if (!(elementType instanceof StructTypeImpl)) {
      throw new IllegalArgumentException(
          "element type must be struct");
    }
    structType = (StructTypeImpl) elementType;
  }
Returns an iterator over the fieldValues Object[] instances
geode-core/src/main/java/org/apache/geode/cache/query/internal/SortedStructSet.java