HSEARCH400609: Unknown field 'attributes.someattributename'

Hibernate Search
4

You are missing a template for your value fields (non-object fields). As a result, when you add a value in your bridge here, Hibernate Search does not have any metadata about the field you’re attempting to add a value for, and cannot determine how to turn the value into JSON:

Define another template for your value fields. Something like this:

public class ResourceAttributesBinder implements PropertyBinder {
    @Override
    public void bind(PropertyBindingContext context) {
        context.dependencies().useRootOnly();
        PojoModelProperty bridgedElement = context.bridgedElement();
        IndexSchemaObjectField attributeField = context.indexSchemaElement()
                .objectField( bridgedElement.name() );

        // ADD THIS
        attributeField.fieldTemplate( 
                "attributeFieldValueTemplate_default",
                f -> f.asString().analyzer( "english" )
        );

        context.bridge(Map.class,new ResourceAttributesPropertyBridge(attributeField.toReference()));
    }
}

Note this is almost exactly the code of the second example in this link that I gave you in answer to your other question.