private StructTypeImpl createStructTypeForNullProjection(List currentIterators,
      ExecutionContext context) {
    int len = currentIterators.size();
    String[] fieldNames = new String[len];
    ObjectType[] fieldTypes = new ObjectType[len];
    String fldName = null;
    for (int i = 0; i < len; i++) {
      RuntimeIterator iter = (RuntimeIterator) currentIterators.get(i);
      // fieldNames[i] = iter.getName();
      if ((fldName = iter.getName()) == null) {
        fldName = generateProjectionName(iter, context);
      }
      fieldNames[i] = fldName;
      fieldTypes[i] = iter.getElementType();
    }
    return new StructTypeImpl(fieldNames, fieldTypes);
  }
This function should be used to create a StructType for those queries which have * as
projection attribute (implying null projection attribute) & multiple from clauses
geode-core/src/main/java/org/apache/geode/cache/query/internal/CompiledSelect.java