@Test
  public void containsKey() throws Exception {
    try (final KeyValueStorage store = createStore()) {
      final byte[] key = bytesFromHexString("ABCD");
      final byte[] value = bytesFromHexString("DEFF");

      assertThat(store.containsKey(key)).isFalse();

      final KeyValueStorageTransaction transaction = store.startTransaction();
      transaction.put(key, value);
      transaction.commit();

      assertThat(store.containsKey(key)).isTrue();
    }
  }
Contains key.

@throws Exception the exception
testutil/src/main/java/org/hyperledger/besu/kvstore/AbstractKeyValueStorageTest.java