public Builder mergeZoneDistributionConfig(
        com.google.cloud.memorystore.v1.ZoneDistributionConfig value) {
      if (zoneDistributionConfigBuilder_ == null) {
        if (((bitField0_ & 0x00080000) != 0)
            && zoneDistributionConfig_ != null
            && zoneDistributionConfig_
                != com.google.cloud.memorystore.v1.ZoneDistributionConfig.getDefaultInstance()) {
          getZoneDistributionConfigBuilder().mergeFrom(value);
        } else {
          zoneDistributionConfig_ = value;
        }
      } else {
        zoneDistributionConfigBuilder_.mergeFrom(value);
      }
      if (zoneDistributionConfig_ != null) {
        bitField0_ |= 0x00080000;
        onChanged();
      }
      return this;
    }
<pre>
Optional. Immutable. Zone distribution configuration of the instance for
node allocation.
</pre>

<code>
.google.cloud.memorystore.v1.ZoneDistributionConfig zone_distribution_config = 18 [(.google.api.field_behavior) = OPTIONAL, (.google.api.field_behavior) = IMMUTABLE];
</code>
java-valkey/proto-google-cloud-valkey-v1/src/main/java/com/google/cloud/memorystore/v1/Instance.java