[meta] 7.0.0 GA release

Meta ticket for 7.0.0 GA

PRs

• Secure String - https://github.com/elastic/elasticsearch-net/pull/3825
• Dynamic cluster state - https://github.com/elastic/elasticsearch-net/pull/3824
• Upgrade assistant - https://github.com/elastic/elasticsearch-net/pull/3822
• Serialisation - https://github.com/elastic/elasticsearch-net/pull/3815
• Low level deprecated paths - https://github.com/elastic/elasticsearch-net/pull/3814
• DiagnosticSource support

Other

• Check nuspec inclusion with DiagnosticSource
• Breaking changes list (generate from published artifact)
  • Documentation change to 7.x
• Go through the Elasticsearch 7.0.0 release notes
• Write release notes for NEST / Elasticsearch.Net clients
• Blog post for release, major topics
  • Serialisation
  • IsValid changes
  • Types removal
  • DiagnosticSource
  • Namespacing (+Upgrade Assistant)
  • Response Interfaces are gone
  • High to Low level dispatch changes
• Ensure TODOs are addressed in codebase
• Check Obsolete usage - https://github.com/elastic/elasticsearch-net/pull/3880
• Review Target Frameworks (netstandard, check possiblity for net461 / netcoreapp2.2)
• Highlight field deserialisation refactoring

[russcam]

@Mpdreamz @codebrain do we want to consider the Diagnostics changes (https://github.com/elastic/elasticsearch-net/issues/3564) for 7.0 GA? Implementation may have impliciations the audit implementation

[saniokOnta]

I have just installed the 7.0.0-beta1 and seen that all ElasticClient responses are concrete classes instead of interfaces.

We cannot mock the ElasticClient methods for unit testing anymore, because the response types have internal Set for their properties.

How would we create unit tests for types which use IElasticClient? Any idea?