Format the code following Google Java Style Guide

[MaicolAntali]

Reformatted all source files with google-java-format as mentioned in #2284

[MaicolAntali]

Some tests fails, but the issue it's related with the order of the fields in the classes.

For exemple the test: ExposeFieldsTest.testArrayWithOneNullExposeFieldObjectSerialization fails due: expected:<[{"[a":1,"d":2.0},{"d":2.0},{"a":2,"d":2.0]}]> but was:<[{"[d":2.0,"a":1},{"d":2.0},{"d":2.0,"a":2]}]>

The issue here come from the object field order. The class before formatting following the google style giude:

  private static class ClassWithExposedFields {
    @Expose private final Integer a;
    private final Integer b;
    @Expose(serialize = false) final long c;
    @Expose(deserialize = false) final double d;
    @Expose(serialize = false, deserialize = false) final char e;

...

and after:

private static class ClassWithExposedFields {
    @Expose(serialize = false) final long c;
    @Expose(deserialize = false) final double d;
    @Expose(serialize = false, deserialize = false) final char e;
    @Expose private final Integer a;
    private final Integer b;

...

In this case is it better to keep the class in the "old" way or fix the test?
(It’s the same for the other failed tests)

[eamonnmcmanus]

As mentioned (somewhat hidden) in the issue, I think we should do this reformatting last, after we've addressed the other things such as migrating tests to JUnit 4. But this is still a useful experiment because we certainly wouldn't expect test failures. Did google-java-format reorder those fields? I don't think the Google style guide requires package fields to come before private ones, so that would be a bug. But also, the order in which fields are returned by reflection is explicitly not ordered so it may be that the failing tests are making invalid assumptions.

[Marcono1234]

Did google-java-format reorder those fields? I don't think the Google style guide requires package fields to come before private ones, so that would be a bug.

It looks like multiple methods and nested classes were reordered as well. The style guide says:

However, there's no single correct recipe for how to do it; different classes may order their contents in different ways.

Personally I also think that no specific ordering should be enforced; that would be too strict and would be more than just formatting.

---

But also, the order in which fields are returned by reflection is explicitly not ordered so it may be that the failing tests are making invalid assumptions.

Probably related to #617. It looks like the majority of Gson's reflection based tests depend on a consistent order.