// a network host (e.g. "foo.bar.com") or "wildcard", which is a domain name
  // prefixed with a single wildcard label (e.g. "*.foo.com").
  // The wildcard character '*' must appear by itself as the first DNS label and
  // matches only a single label. You cannot have a wildcard label by itself (e.g. Host == "*").
  // Requests will be matched against the Host field in the following way:

  // a network host (e.g. "foo.bar.com") or "wildcard", which is a domain name
  // prefixed with a single wildcard label (e.g. "*.foo.com").
  // The wildcard character '*' must appear by itself as the first DNS label and
  // matches only a single label. You cannot have a wildcard label by itself (e.g. Host == "*").
  // Requests will be matched against the Host field in the following way:

  // a network host (e.g. "foo.bar.com") or "wildcard", which is a domain name
  // prefixed with a single wildcard label (e.g. "*.foo.com").
  // The wildcard character '*' must appear by itself as the first DNS label and
  // matches only a single label. You cannot have a wildcard label by itself (e.g. Host == "*").
  // Requests will be matched against the Host field in the following way:

  // '*' means all resources, but not subresources.
  // 'pods/*' means all subresources of pods.
  // '*/scale' means all scale subresources.
  // '*/*' means all resources and their subresources.
  //
  // If wildcard is present, the validation rule will ensure resources do not
  // overlap with each other.
  //
  // Depending on the enclosing object, subresources might not be allowed.
  // Required.
  // +listType=atomic

  // +optional
  optional string key = 1;

  // Operator represents a key's relationship to the value.
  // Valid operators are Exists and Equal. Defaults to Equal.
  // Exists is equivalent to wildcard for value, so that a pod can
  // tolerate all taints of a particular category.
  // +optional
  optional string operator = 2;

  // Value is the taint value the toleration matches to.