Previously external/libphonenumber accepted lower case country codes (e.g. "us") but now it doesn't for performance reason. Actually ISO 3166-1 doesn't allow lower cases, so we should not rely on them. Need to fix unit tests for PhoneNumberUtils, as it implicitly relies on the previous behavior. See also I3a3e6db84ed0d24290b1be19651fa9a82de4cc39 Bug: 4941319 Change-Id: If16f6531f274a0faf5e28724854409ca9b00a669