Always send internal_ip_only, if it is set by the user.

This is required because the autogenerated Dataproc API client has `omitempty` on the field. So if the user specifies `internal_ip_only: false`, then it would not get sent to Dataproc. Thus Dataproc uses server-side defaulting. We don't want that. If the user specifies the value, we want to ensure that value is used.

mmv1/third_party/terraform/services/dataproc/resource_dataproc_cluster.go

@@ -2177,7 +2177,13 @@ func expandGceClusterConfig(d *schema.ResourceData, config *transport_tpg.Config
 	}
 	if v, ok := cfg["internal_ip_only"]; ok {
 		conf.InternalIpOnly = v.(bool)
+		// Normally default values are omitted. Concretely this means that if v is
+		// false, then it would not get sent on the request to Dataproc. However,
+		// the user has explicitly set internal_ip_only, therefore we need to send
+		// it on the wire to ensure Dataproc does not use server-side defaulting.
+		conf.ForceSendFields = append(conf.ForceSendFields, "InternalIpOnly")
 	}
+
 	if v, ok := cfg["metadata"]; ok {
 		conf.Metadata = tpgresource.ConvertStringMap(v.(map[string]interface{}))
 	}