@Override
    public Class[] getParameterTypes() {
        return new Class[] { SampleFamily.class};
    }
getParameterTypes hints the right-hand side should be {@link SampleFamily}.

@return the class array contains argument type.
oap-server/analyzer/meter-analyzer/src/main/java/org/apache/skywalking/oap/meter/analyzer/dsl/NumberClosure.java