* Enable additional Error Prone checks & fix violations
Some of them also enforce additional Google Java Format requirements which
are not handled by google-java-format, such as disallowing wildcard imports.
Not all experimental checks have been listed because some are not applicable,
such as Dependency Injection framework checks, or checks related to Guava's
immutable collections (since Gson's main code does not have a dependency on
Guava).
Other checks have been omitted because they are probably not relevant
(this was a subjective choice), or would require larger refactoring or
would flag issues with the public API, which cannot be changed easily.
* Address review feedback
---------
Co-authored-by: Éamonn McManus <emcmanus@google.com>
This annotation indicates that return value of the annotated method does
not need to be used. If it is _not_ present on a non-void method, and if
Error Prone's `CheckReturnValue` is active, then calling the method
without using the result is an error. However, we are not enabling
`CheckReturnValue` by default here.
Also update some code that does ignore return values, so that the
returned value is used, if only by assigning it to an unused variable.
* Port Junit assert to Truth in `com.google.gson.stream`
* Port Junit assert to Truth in `com.google.gson.regression`
* Port Junit assert to Truth in `om.google.gson.reflect`
* Port Junit assert to Truth in `com.google.gson.metrics`
* Port Junit assert to Truth in `com.google.gson.internal`
* Port Junit assert to Truth in `com.google.gson.internal.sql`
* Port Junit assert to Truth in `com.google.gson.internal.reflect`
* Port Junit assert to Truth in `com.google.gson.internal.bind`
* Port Junit assert to Truth in `com.google.gson.internal.bind.util`
* Port Junit assert to Truth in `com.google.gson.functional`
* Replaces `List.of` with `Arrays.asList` to grant legacy
* Simplify `==` asserts
* Simplify `.contain()` asserts + Minor fixes
* Simplify asserts
Marcono1234