#vulnerable code 
                                public boolean isIterableMapping() {
        return getSingleSourceType().isIterableType() && resultType.isIterableType();
    } 
                            #location 2 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                public boolean isIterableMapping() {
        return getSingleSourceParameter().getType().isIterableType() && getResultType().isIterableType();
    }