private static String removePrefix(String expectedPrefix, String kmsKeyUri) {
    if (!kmsKeyUri.toLowerCase(Locale.US).startsWith(expectedPrefix)) {
      throw new IllegalArgumentException(
          String.format("key URI must start with %s", expectedPrefix));
    }
    return kmsKeyUri.substring(expectedPrefix.length());
  }
Specifies the {@link com.amazonaws.services.kms.AWSKMS} object to be used. Only used for
testing.
java_src/src/main/java/com/google/crypto/tink/integration/awskms/AwsKmsClient.java