private static void exportRemoveFieldValue(Writer out, int ind) throws IOException {
        out.write(ind(ind) + "@Override public com.yahoo.document.datatypes.FieldValue removeFieldValue(com.yahoo.document.Field field) {\n");
        out.write(ind(ind+1) + "if (field==null) return null;\n");
        out.write(ind(ind+1) + "com.yahoo.document.ExtendedField ef = ensureExtended(field);\n");
        out.write(ind(ind+1) + "return (ef != null) ? ef.setFieldValue(this, null) : super.removeFieldValue(field);\n");
        out.write(ind(ind) + "}\n");
    }
Exports the necessary overridden methods from Document/StructuredFieldValue
vespa-documentgen-plugin/src/main/java/com/yahoo/vespa/DocumentGenMojo.java