EnumOrdinal - Error Prone

You should almost never invoke the Enum.ordinal() method, nor depend on some enum constant being at a particular index of the values() array. The ordinal of a given enum value is not guaranteed to be stable across builds because of the potential for enum values to be added, removed, or reordered. The ordinal exists only to support low-level utilities like EnumSet.

Prefer using enum value directly:

java

ImmutableMap<MyEnum, String> MAPPING =
    ImmutableMap.<MyEnum, String>builder()
        .put(MyEnum.FOO, "Foo")
        .put(MyEnum.BAR, "Bar")
        .buildOrThrow();

instead of relying on the ordinal:

java

ImmutableMap<Integer, String> MAPPING =
    ImmutableMap.<Integer, String>builder()
        .put(MyEnum.FOO.ordinal(), "Foo")
        .put(MyEnum.BAR.ordinal(), "Bar")
        .buildOrThrow();

If you need a stable number for serialisation, consider defining an explicit field on the enum:

java

enum MyStableEnum {
  FOO(1),
  BAR(2),
  ;

  private final int wireCode;
  MyStableEnum(int wireCode) {
    this.wireCode = wireCode;
  }
}

rather than relying on the ordinal values:

java

enum MyUnstableEnum {
  FOO,
  BAR,
}
MyUnstableEnum fromWire(int wireCode) {
  return MyUnstableEnum.values()[wireCode];
}