Nexus: checkpoint setting not honored

[prckent]

Describe the bug

Setting checkpoint=-1 ( https://qmcpack.readthedocs.io/en/develop/methods.html#general-qmc-inputs ) as per the following did not result in any checkpoint settings in the generated QMCPACK input XML or an error from Nexus. However Nexus does appear to support the checkpoint keyword. => Is this a missing feature or a bug?

I found this problem due to a need to disable checkpointing in some science runs due to poor I/O times (30 mins to save configs & random seed files on a single node... ).

               dmcJ123_dt01 = generate_qmcpack(
                    identifier    = 'dmc_J123_dt01',
                    path          = Mysystem+'/dmc_J123_dt01',
                    job           = dmc_job,
                    system        = system,
                    pseudos       = 'ccecp',
                    jastrows      = [],
                    qmc           = 'dmc',
                    driver = 'batched',
                    max_seconds = 83000,
                    checkpoint = -1,
                    vmc_warmupsteps = 100,
                    vmc_blocks    = 1,
                    vmc_steps     = 1,
                    eq_dmc        = True,
                    blocks        = 160,
                    steps         = 400,
                    total_walkers = 9600,
                    timestep      = 0.01,
                    nonlocalmoves = "v3",
                    dependencies  = orbdeps+[(optJ123_3,'jastrow')],
                    )

To Reproduce

As above.

Using a version of develop from a few months back.

Expected behavior

Checkpoint=-1 in each driver section.

[jtkrogel]

Missing feature. Plumbing needed.

Should the Nexus default follow the QMCPACK default (checkpoint doesn't appear in input file) or something else (e.g. default to -1)?