presto-main/src/main/java/io/prestosql/server/protocol/ExecutingStatementResource.java/ExecutingStatementResource/partialCancel
class ExecutingStatementResource:    @DELETE
    @Path("/v1/statement/partialCancel/{queryId}/{stage}/{slug}/{token}")
    public void partialCancel(
            @PathParam("queryId") QueryId queryId,
            @PathParam("stage") int stage,
            @PathParam("slug") String slug,
            @PathParam("token") long token)
    {
        Query query = getQuery(queryId, slug, token);
        query.partialCancel(stage);
    }