public Builder setContentTypeBytes(com.google.protobuf.ByteString value) {
      if (value == null) {
        throw new NullPointerException();
      }
      checkByteStringIsUtf8(value);
      contentType_ = value;
      bitField0_ |= 0x00000008;
      onChanged();
      return this;
    }
<pre>
Optional. Updates objects Content-Type fixed metadata. Unset values will be
ignored.
 Set empty values to clear the metadata. Refer to documentation in
 https://cloud.google.com/storage/docs/metadata#content-type
</pre>

<code>optional string content_type = 4 [(.google.api.field_behavior) = OPTIONAL];</code>

@param value The bytes for contentType to set.
@return This builder for chaining.
java-storagebatchoperations/proto-google-cloud-storagebatchoperations-v1/src/main/java/com/google/cloud/storagebatchoperations/v1/PutMetadata.java