public SchemaService( RootNexus nexus, GlobalRegistries globalRegistries )
public SchemaService( RootNexus nexus, GlobalRegistries globalRegistries, FilterService filterService )
    public SchemaService( RootNexus nexus, GlobalRegistries globalRegistries )    {        this.nexus = nexus;        if ( this.nexus == null )        {            throw new NullPointerException( "the nexus cannot be null" );        }        this.globalRegistries = globalRegistries;        if ( this.globalRegistries == null )        {            throw new NullPointerException( "the global registries cannot be null" );        }    }