private com.google.protobuf.SingleFieldBuilderV3<
            com.google.cloud.vertexai.api.MachineSpec,
            com.google.cloud.vertexai.api.MachineSpec.Builder,
            com.google.cloud.vertexai.api.MachineSpecOrBuilder>
        getMachineSpecFieldBuilder() {
      if (machineSpecBuilder_ == null) {
        machineSpecBuilder_ =
            new com.google.protobuf.SingleFieldBuilderV3<
                com.google.cloud.vertexai.api.MachineSpec,
                com.google.cloud.vertexai.api.MachineSpec.Builder,
                com.google.cloud.vertexai.api.MachineSpecOrBuilder>(
                getMachineSpec(), getParentForChildren(), isClean());
        machineSpec_ = null;
      }
      return machineSpecBuilder_;
    }
<pre>
Required. Immutable. The specification of a single machine.
</pre>

<code>
.google.cloud.vertexai.v1.MachineSpec machine_spec = 1 [(.google.api.field_behavior) = REQUIRED, (.google.api.field_behavior) = IMMUTABLE];
</code>
java-vertexai/proto-google-cloud-vertexai-v1/src/main/java/com/google/cloud/vertexai/api/BatchDedicatedResources.java