code: public static RAExpression crossJoin(RAExpression re1, RAExpression re2, TermFactory termFactory) throws IllegalJoinException {
  
          RAExpressionAttributes attributes =
                  RAExpressionAttributes.crossJoin(re1.attributes, re2.attributes);
  
          return new RAExpression(union(re1.dataAtoms, re2.dataAtoms),
                  union(re1.filterAtoms, re2.filterAtoms), attributes, termFactory);
      }
docs: CROSS JOIN (also denoted by , in SQL)
  
  @param re1 a {@link RAExpression}
  @param re2 a {@link RAExpression}
  @return a {@link RAExpression}
  @throws IllegalJoinException if the same alias occurs in both arguments