private boolean isInitialized() {
        return partitionsByTopic != null && !partitionsByTopic.isEmpty() && localMetadata.get() != null;
    }
Respond to changes to the HostInfo -> TopicPartition mapping. Will rebuild the
metadata

@param activePartitionHostMap  the current mapping of {@link HostInfo} -> {@link TopicPartition}s for active partitions
@param standbyPartitionHostMap the current mapping of {@link HostInfo} -> {@link TopicPartition}s for standby partitions
@param topicPartitionInfo      the current mapping of {@link TopicPartition} -> {@Link PartitionInfo}
streams/src/main/java/org/apache/kafka/streams/processor/internals/StreamsMetadataState.java