private boolean isValidSystemName(String id) {
    return StringUtils.isNotBlank(id) && SYSTEM_NAME_PATTERN.matcher(id).matches();
  }
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