code: public <E> E get(PartitionKey key, EntityMapper<E> entityMapper) {
      return get(key, null, entityMapper);
    }
docs: Execute a Get on HBase, creating the Get from the key's toByteArray method.
  The returned Result of the Get will be mapped to an entity with the
  entityMapper, and that entity will be returned.
  
  Any GetModifers registered with registerGetModifier will be invoked before
  the Get is executed.
  
  @param key
  The StorageKey to create a Get from.
  @param entityMapper
  The EntityMapper to use to map the Result to an entity to return.
  @return The entity created by the entityMapper.