String genFromClause(ExecutionContext context)
      throws TypeMismatchException, NameResolutionException {
    StringBuilder sbuff = new StringBuilder();
    collectionExpr.generateCanonicalizedExpression(sbuff, context);
    return sbuff.toString();
  }
Convert the given object to a SelectResults. Must be a collection of some sort. The obj passed
in must be unmodified, but the resulting SelectResults may or may not be modifiable. Return
null if obj is null or UNDEFINED.
geode-core/src/main/java/org/apache/geode/cache/query/internal/CompiledIteratorDef.java