public Map<String, String> readExecutionEnvironmentContainerIdMapping() {
    Map<String, String> executionEnvironmentContainerIdMapping = new HashMap<>();
    metadataStore.all().forEach((processorId, valueBytes) -> {
      if (valueBytes != null) {
        String executionEnvContainerId = valueSerde.fromBytes(valueBytes);
        executionEnvironmentContainerIdMapping.put(processorId, executionEnvContainerId);
      }
    });
    if (LOG.isDebugEnabled()) {
      for (Map.Entry<String, String> entry : executionEnvironmentContainerIdMapping.entrySet()) {
        LOG.debug("Processor {} has executionEnvContainerId as {}", entry.getKey(), entry.getValue());
      }
    }
    return executionEnvironmentContainerIdMapping;
  }
Builds the ExecutionContainerIdManager based upon the provided {@link MetadataStore} that is instantiated.
Uses the {@link CoordinatorStreamValueSerde} to serialize messages before reading/writing into metadata store.
@param metadataStore an instance of {@link MetadataStore} to read/write the processor container id mapping.
samza-core/src/main/java/org/apache/samza/container/ExecutionContainerIdManager.java