* Avoid initializing primitive fields in layout_init

* Avoid initializing string/bytes/message fields in layout_init

* Lazily create map when needed

* Lazily create repeated fields

* Change layout_init to only do memcpy

* Fix test for php-7.0

* Fix conformance test where default value of string/message map is not encoded

* Fix test for zts

* Clean up

* Fix comments

Update GSON and errorprone

Update to 3.10.0 in docs

This way, we can avoid an unnecessary copy.

merge

Down integrate Google3 changes to Github

Installing BOM before running Java test

Add com.google.truth as test dependencies

This goes hand-in-hand with other dependencies like junit, but seems to
only have been used from util/pom.xml.

Add length checks to ExtensionCollection

c# feature(RepeatedField): Capacity property to resize the internal array

Remove unused argument to avoid UB

This fixes build on, at least, NetBSD 8.1 with gcc 5.5 and SmartOS with gcc 7.

Java: Update to Guava 28.1-android

Fixed bug in Ruby DSL when no names are defined in a file.

Ported names fix for Ruby to the release branch.

`OneOfDescriptor_each` is registered as a Ruby method which takes zero
parameters, which means it should take one argument.

When Ruby invokes `OneOfDescriptor_each`, it calls it with one parameter
only, which is one less than what `OneOfDescriptor_each` takes before
this commit. Calling a function with the wrong number of argument is
technically undefined behavior.

See also: §6.5.2.2, N1256