public Builder mergeStart(com.google.cloud.visionai.v1.FacetValue value) {
        if (startBuilder_ == null) {
          if (((bitField0_ & 0x00000001) != 0)
              && start_ != null
              && start_ != com.google.cloud.visionai.v1.FacetValue.getDefaultInstance()) {
            getStartBuilder().mergeFrom(value);
          } else {
            start_ = value;
          }
        } else {
          startBuilder_.mergeFrom(value);
        }
        if (start_ != null) {
          bitField0_ |= 0x00000001;
          onChanged();
        }
        return this;
      }
<pre>
Start of the range. Non-existence indicates some bound (e.g. -inf).
</pre>

<code>.google.cloud.visionai.v1.FacetValue start = 1;</code>
java-visionai/proto-google-cloud-visionai-v1/src/main/java/com/google/cloud/visionai/v1/FacetBucket.java