Certain APIs and classes retain or return bytearrays
which can be mutated by the callers.

1. Use @Immutable annotations to statically check
   if a class exposes any mutable data.
2. Add an ImmutableByteArray class that prevents mutable
   bytearrays by making or returning a copy of an underlying
   set of bytes.

Change-Id: I2c5804eeb3d2e736eb45bb3283979b2874b5d7b4
ORIGINAL_AUTHOR=KB Sriram <kbsriram@google.com>
GitOrigin-RevId: 1c9804a2101360ddf41db719eef1d763e965d9ed

ORIGINAL_AUTHOR=Thai Duong <thaidn@google.com>
GitOrigin-RevId: 3989554f6b1639b744f7a188f5972f8f03d4ee79

Change-Id: I9fd2751bb08260ea33a5c1bb48f0eae0f13be577
ORIGINAL_AUTHOR=Thai Duong <thaidn@google.com>
GitOrigin-RevId: 7cdb027541f9cd760e91713deed0d9915cb7fc61

Also funny: macOS thinks BUILD and build are the same, thus cannot have a build
folder.

Change-Id: I61ba19a31590f03c2e8b2a78bf2d89a539afc938
ORIGINAL_AUTHOR=Thai Duong <thaidn@google.com>
GitOrigin-RevId: b07bcab62dae4b979f03dce35b45da5345936c93

Also adds Google truth library for tests.

Change-Id: I032ecce6b3f492f2693c7b7a5534450b9465d1ae
ORIGINAL_AUTHOR=Erhan Nergiz <anergiz@google.com>
GitOrigin-RevId: 6cc7462b634384bd06bb9fc1ac7f8b8d201d7284

ORIGINAL_AUTHOR=Thai Duong <thaidn@google.com>
GitOrigin-RevId: fb88b09207a8ff3e62e6068075319d09c74901b4

Change-Id: I7b23beb90b3a4e6deef266757750fd40fb585579
ORIGINAL_AUTHOR=Bartosz Przydatek <przydatek@google.com>
GitOrigin-RevId: a6bcabcc16601d22c528a93213a790c1fba17f2e

Change-Id: If828650e8a8e0ed93f65d582040df0fd5ac5ed5d
ORIGINAL_AUTHOR=Bartosz Przydatek <przydatek@google.com>

GitOrigin-RevId: e2ff2438034b5f6bc04f536f59b491ff0c6abbee

command works

bazel build //tools/...

./bazel-bin/tools/tinkey/tinkey envelope --dek-type AesGcm --dek-format
"key_size: 32" --google-cloud-kms-key-uri
projects/foo/locations/global/keyRings/bar/cryptoKeys/foobar --out
tink.cfg

cat tink.cfg

Change-Id: Ib3b37ac35d17686c63eeb3f6d1c7897475d30ab3
ORIGINAL_AUTHOR=Thai Duong <thaidn@gmail.com>

GitOrigin-RevId: b284aa1a0bad6556c65208d15f12e0abe93fc780

Change-Id: I8c930658fc875538952b21a59892264dad3186af
ORIGINAL_AUTHOR=Thai Duong <thaidn@google.com>

GitOrigin-RevId: 5d016e5ce6c41edf7204549bcd39fe3053d84f5c

automating generation of test rules for Java tests.

GenTestRules.bzl copied from
https://gist.github.com/jart/9a9f48e216fd747275012d2f2364ac09. I
modified to make it recognize src/java/test/ as a prefix (in addition to
javatests/ and java/).

Bazel developer explained why this is optimal:
https://groups.google.com/d/msg/bazel-discuss/MFYYkJk1tFs/xltlv4m_AQAJ.

Change-Id: I8ff9d48b994efa9e7ed7a1e2c7b8afed8a05b94a
ORIGINAL_AUTHOR=Thai Duong <thaidn@gmail.com>

GitOrigin-RevId: 9abc2685664a9f85ceca6835827219531ac8c6c6

Change-Id: I0377e32aea55c3e85a40bc64eddf45c52846cac6
ORIGINAL_AUTHOR=Bartosz Przydatek <przydatek@google.com>

GitOrigin-RevId: c80cbaaf25e74ab8a7595e5192628d0f5d993a4c

- Directory structure follows TensorFlow.
- Rules for protobuf building are based on https://github.com/pubref/rules_protobuf, as I can't find anything simpler.
- Continuous integration with Kokoro (work in progress).

I also copied some existing Java/CC code from Bartosz and Daniel's experimental folders.

Change-Id: I7f993934d149c114320e3388fee84fbdafd7ba81