In SpatialFieldBridge, there is a default implementation of configureFieldMetadata which does not provide information about the fields really added in the child classes of SpatialFieldBridge:

        @Override
	public void configureFieldMetadata(String name, FieldMetadataBuilder builder) {
		builder.field( name, FieldType.DOUBLE )
			.sortable( true );
	}

It looks like an oversight.

Each child classes should implement configureFieldMetadata and provide information about the fields they really add.