private boolean mustBeOverriddenInProxyDocument(Method m) {
        if (!Modifier.isPublic(m.getModifiers())) return false;
        if (Modifier.isStatic(m.getModifiers())) return false;
        if (Modifier.isFinal(m.getModifiers())) return false;
        return true;
    }
To make it less likely to break schema mapping, we enforce that ProxyDocument does wrap every public
non-static, non-final method on Document and StructuredFieldValue
docproc/src/test/java/com/yahoo/docproc/proxy/SchemaMappingAndAccessesTest.java