[pull] main from objectbox:main - #18

Instead of asserting some very specific sizes and messages that are not
really of importance, ensure the APIs fulfill reasonable expectations.

Also drop braces on conditionals where they weren't for readability.
Reduce visibility if possible.

These are a time waste. Rather spend time on adding tests to the Gradle
plugin and the integration tests.

Also update Nexus Publish plugin [1.3.0 -> 2.0.0]

Also remove large timeouts, new Maven Central infrastructure is fast.

…checker thread #240

…#240

This prevents an "Another BoxStore is still open for this directory"
exception when a previous instance using the same directory has to be
finalized (because it wasn't closed explicitly).

BoxStore: when constructing, actually wait on finalization of other instances #240

See merge request objectbox/objectbox-java!161

Also prepare to customize the regular output stream, but do not add a
builder API until it is required.

…#258

Previously Thread.dumpStack() was used which only prints the stack of
the current thread. Also *all* existing threads were printed, not just
those from the internal thread pool.

Best practice Java. Also prevent public access to internalThreadPool().

…258

This can help avoid transactions getting closed by force.

…258

BoxStore: improve thread pool shutdown, error messages #258

See merge request objectbox/objectbox-java!147

This was deprecated in release 4.0.3

This was deprecated in release 3.7.0

This was deprecated in release 3.7.0

As a positive side effect this avoids pulling in the additional Android
API artifact for the ObjectBox Flutter package.

This reverts commit 8fe8f79.

That the method currently calls the retryNetworks method may change in
the future.

This is used on Android only, so using Kotlin with its null-safe types
is preferred.