in auth/src/main/java/com/google/firebase/quickstart/AuthSnippets.java [45:52]
public static void getUserByPhoneNumber(
String phoneNumber) throws InterruptedException, ExecutionException {
// [START get_user_by_phone]
UserRecord userRecord = FirebaseAuth.getInstance().getUserByPhoneNumberAsync(phoneNumber).get();
// See the UserRecord reference doc for the contents of userRecord.
System.out.println("Successfully fetched user data: " + userRecord.getPhoneNumber());
// [END get_user_by_phone]
}