public Builder setKeyBytes(com.google.protobuf.ByteString value) {
      if (value == null) {
        throw new NullPointerException();
      }
      checkByteStringIsUtf8(value);
      key_ = value;
      bitField0_ |= 0x00000002;
      onChanged();
      return this;
    }
<pre>
Optional. Corresponds to the label key of a reservation resource. To target
a SPECIFIC_RESERVATION by name, use
`compute.googleapis.com/reservation-name` as the key and specify the name
of your reservation as its value.
</pre>

<code>string key = 2 [(.google.api.field_behavior) = OPTIONAL];</code>

@param value The bytes for key to set.
@return This builder for chaining.
java-vertexai/proto-google-cloud-vertexai-v1/src/main/java/com/google/cloud/vertexai/api/ReservationAffinity.java