src/main/java/com/conveyal/gtfs/graphql/GTFSGraphQL.java
public static void initialize (DataSource dataSource) {
        GTFSGraphQL.dataSource = dataSource;
        GRAPHQL = GraphQL.newGraphQL(GraphQLGtfsSchema.feedBasedSchema)
            .build();
    }
public static void initialize (DataSource dataSource) {
        GTFSGraphQL.dataSource = dataSource;
        GRAPHQL = GraphQL.newGraphQL(GraphQLGtfsSchema.feedBasedSchema)
            .build();
    }
Username and password can be null if connecting to a local instance with host-based authentication.