@Override
    public void run() {
      try {
        for (int i = 0; i < count; i++) {
          byte[] signature = signer.sign(message);
          signatures.add(Hex.encode(signature));
        }
      } catch (Exception ex) {
        getUncaughtExceptionHandler().uncaughtException(this, ex);
      }
    }
Read the plaintext from the channel. This implementation assumes that the channel is blocking
and throws an AssertionError if an attempt to read plaintext from the channel is incomplete.
java_src/src/test/java/com/google/crypto/tink/subtle/SignatureThreadSafetyTest.java