private void ensureItemsIsMutable() {
      if (!((bitField0_ & 0x00000004) != 0)) {
        items_ =
            new java.util.ArrayList<com.google.cloud.speech.v1p1beta1.CustomClass.ClassItem>(
                items_);
        bitField0_ |= 0x00000004;
      }
    }
<pre>
If this custom class is a resource, the custom_class_id is the resource id
of the CustomClass. Case sensitive.
</pre>

<code>string custom_class_id = 2;</code>

@param value The bytes for customClassId to set.
@return This builder for chaining.
java-speech/proto-google-cloud-speech-v1p1beta1/src/main/java/com/google/cloud/speech/v1p1beta1/CustomClass.java