Discuss V7 deprecations

[DannyvdSluijs]

This discussion is to keep track of possible deprecations for V7. Feel free to contribute with feedback, suggestions for new deprecations and anything related to deprecations in V7.
Once a deprecation is decided final it should be marked as such in V6 before we can remove in V7.

Drop support for associative arrays

Status: undecided
Description: Associative arrays have been troublesome for some time. We aren't explicit in what we do or do not support. Resulting in discussions as we can see in #767, #780, #784, #786

Drop nullable support for $schema in Validator::Validate

Status: undecided
Description: As it seems a schema should always be required, also see #541

Drop Validator::coerce

Status: undecided
Description: As mentioned in code this method is there for backwards-compatibility with the previous api which means we could drop it in the next mayor version.

Drop support for inline schemas

Status: undecided
Description: As mentioned by @shmax in #541 (comment) we are currently supporting inline array of objects for the $schema property which isn't allowed accordingly to the specs. These inline schemas seems to be supported since one of the earliest versions of 17 years ago which even pre-dates the official JSON schema specifications (Draft 0 is dated 2009-12-05)