public Builder clearManifestKey() {
        manifestKey_ = getDefaultInstance().getManifestKey();
        bitField0_ = (bitField0_ & ~0x00000001);
        onChanged();
        return this;
      }
<pre>
Required. A unique key that identifies a manifest config in the parent
channel. This key is the same as `channel.manifests.key` for the selected
manifest.
</pre>

<code>string manifest_key = 1 [(.google.api.field_behavior) = REQUIRED];</code>

@return This builder for chaining.
java-video-live-stream/proto-google-cloud-live-stream-v1/src/main/java/com/google/cloud/video/livestream/v1/DvrSession.java