private void ensureNoiseSigmaIsMutable() {
      if (!((bitField0_ & 0x00000001) != 0)) {
        noiseSigma_ =
            new java.util.ArrayList<
                com.google.cloud.vertexai.api.FeatureNoiseSigma.NoiseSigmaForFeature>(noiseSigma_);
        bitField0_ |= 0x00000001;
      }
    }
<pre>
Noise sigma by features. Noise sigma represents the standard deviation of the
gaussian kernel that will be used to add noise to interpolated inputs prior
to computing gradients.
</pre>

Protobuf type {@code google.cloud.vertexai.v1.FeatureNoiseSigma}
java-vertexai/proto-google-cloud-vertexai-v1/src/main/java/com/google/cloud/vertexai/api/FeatureNoiseSigma.java