public SubClass withDefaultStreamConfigs(Map<String, String> defaultStreamConfigs) {
    this.defaultStreamConfigs.putAll(defaultStreamConfigs);
    return (SubClass) this;
  }
Default properties for any stream obtained using this system descriptor.
<p>
For example, if "systems.kafka-system.default.stream.replication.factor"=2 was configured,
then every Kafka stream created on the kafka-system will have a replication factor of 2
unless the property is explicitly overridden using the stream descriptor.

@param defaultStreamConfigs default stream properties
@return this system descriptor
samza-api/src/main/java/org/apache/samza/system/descriptors/SystemDescriptor.java