Provide Schemas for JSON services

[rhwood]

We need to be able to provide JSON schemas to developers of third party applications that might interact with JMRI. This will provide a machine-readable and in-code verifiable mechanism for documenting precisely what a JMRI JSON service will provide. Providing schemas within the JMRI application web server will allow clients to interrogate specific capabilities of a JMRI instance to (for example) determine if a specific third-party plugin has been installed.

This requires:

• Initial implementation of serving schemas from within a JMRI instance (Add JSON Schemas #5003)
• Providing core schemas via the JMRI.org website (to allow other schemas to reference them)
• Creating cross-referenced schemas (to reduce the possibility of contradictory schemas due to duplication)

[rhwood]

OP is no longer concerned.

[rhwood]

This is blocked by #6840 which would allow the schema to be published (or even not published but referenced to as if they are published) and cross-referenced.

[rhwood]

As of #6901, all schema except the consist schema are expected to be mostly correct, if somewhat vague when incorporating another schema. Once #6840 is incorporated that vagueness can be addressed.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. JMRI is governed by a small group of maintainers which means not all opened issues may receive direct feedback.

[stale]

This issue has been automatically closed due to lack of activity. In an effort to reduce noise, please do not comment any further. Note that the maintainers may elect to reopen this issue at a later date if deemed necessary.