Update MLM JSON schema to enforce mlm:input band checks as intended

[fmigneault]

Description

Warning

If an existing MLM definition was succeeding with https://github.com/crim-ca/mlm-extension/tree/v1.2.0, it might fail with this revision due to the stricter validation of bands. Older definitions could be considered "incomplete" from the missing "bands" reference if they were not employing other extensions properly (see https://github.com/crim-ca/mlm-extension/tree/fix-comments#bands-and-statistics for details).

Added

• Add raster:bands required property name for describing mlm:input bands
  (see https://github.com/crim-ca/mlm-extension/tree/fix-comments#bands-and-statistics) for details).
• Add README warnings about new extension eo and raster versions.

Changed

• Split ModelBands and AnyBandsRef definitions in the JSON schema to allow them to be referenced individually.
• Move AnyBandsRef definition explicitly to STAC Item JSON schema, rather than implicitly inferred via mlm:input.
• Modified the JSON schema to use a if check of the type (STAC Item or Collection) prior to validating further
  properties. This allows some validators (e.g. pystac) to better report the real error that causes the schema
  to fail, rather than reporting the first mismatching type case with a poor error description to debug the issue.

Deprecated

• n/a

Removed

• Removed $comment entries from the JSON schema that are considered as invalid by some parsers.
• When mlm:input objects do NOT define band references (i.e.: bands: [] is used), the JSON schema will not
  fail if an Asset with the mlm:model role contains a band definition. This is to allow MLM model definitions to
  simultaneously use some inputs with bands reference names while others do not.

Fixed

• Band checks against eo, raster or STAC Core 1.1 bands when a mlm:input references names in bands are now properly validated.
• Fix the examples using raster:bands incorrectly defined in STAC Item properties.
  The correct use is for them to be defined under the STAC Asset using the mlm:model role.
• Fix the https://github.com/crim-ca/mlm-extension/blob/fix-comments/stac_model/examples.py that incorrectly referenced some bands in its mlm:input definition without providing any definition of those bands. The eo:bands properties have been added to the corresponding model Asset using the pystac.extensions.eo utilities.
• Fix various STAC Asset definitions erroneously employing mlm:model role instead of the intended mlm:source_code.

Related Issue

• closes remove comments for online validators #38

Type of Change

• 📚 Examples, docs, tutorials or dependencies update;
• 🔧 Bug fix (non-breaking change which fixes an issue);
• 🥂 Improvement (non-breaking change which improves an existing feature);
• 🚀 New feature (non-breaking change which adds functionality);
• 💥 Breaking change (fix or feature that would cause existing functionality to change);
• 🔐 Security fix.

Checklist

• I've read the CONTRIBUTING.md guide;
• I've updated the code style using make check;
• I've written tests for all new methods and classes that I created;
• I've written the docstring in Google format for all the methods and classes that I used.

[fmigneault]

@rbavery FYI
I'm still working on this...

I've realized that by enabling the following:

mlm-extension/json-schema/schema.json

Lines 53 to 56 in 5212acf

	{
	"$comment": "Schema to validate cross-references of bands between MLM inputs and any 'bands'-compliant section describing them using another STAC definition.",
	"$ref": "#/$defs/AnyBandsRef"
	},

... many of the "band" checks across EO/Raster/STAC-core were actually incorrect, as well as some of the provided examples.

For example,

mlm-extension/examples/item_raster_bands.json

Line 208 in 6338f4d

"raster:bands": [

uses raster:bands at the Item properties level, when they MUST be under an Asset according to raster extension.

Similarly, https://github.com/crim-ca/mlm-extension/blob/v1.2.0/stac_model/examples.py defined mlm:input with some bands, but they were never actually validated correctly. I've added the https://github.com/stac-utils/pystac/blob/main/pystac/extensions/eo.py extension wrapper to it, to maek it work correctly with band checks.

[fmigneault]

@rbavery
Forgot to ping you again. The PR is ready now.
Let me know if it works with your examples whenever you have some time.

[fmigneault]

Merging and will pin as v1.3.0 to avoid dealing with the integration before move to https://github.com/stac-extensions/mlm.
If anything doesn't work, a v1.3.1 could be considered, or users can refer to the v1.2.0 in the meantime.