@Override
  public void put(String key, byte[] value) {
    String coordinatorMessageKeyAsJson = getCoordinatorMessageKey(key);
    metadataStore.put(coordinatorMessageKeyAsJson, value);
  }
Instantiates the {@link NamespaceAwareCoordinatorStreamStore} based upon the provided
MetadataStore that is instantiated and the namespace.

@param metadataStore the instantiated {@link MetadataStore}.
@param namespace the namespace to use for storing the keys in the metadata store.
samza-core/src/main/java/org/apache/samza/coordinator/metadatastore/NamespaceAwareCoordinatorStreamStore.java