Evaluation of how Kubebuilder markers affect whether items are required or optional

kubebuilder-optional-or-required.md

// The [KubeBuilder documentation]
// (https://book.kubebuilder.io/reference/markers/crd-validation.html?highlight=required#crd-validation)
// states that if you include the kubebuilder:validation:Required marker at the
// packate level as shown below, all fields in the package are required unless
// explicitly marked optional.  However, it doesn't seem to make a difference.
// Without it, all fields that aren't explicitly marked as optional are treated
// as required anyway.
// +kubebuilder:validation:Required
package v1alpha1

type ApiTest struct {
	// This field is optional since we included the +optional and omitempty
	// markers.  It is not be included in the serialized output if empty because
	// we inluded omitembpty.  Best practice is to use both markers together.
	// When omitted, the default value is zero (the default for the int type).
	// +optional
	OptionalField1 int `json:"optionalField1,omitempty"`

	// This field is optional since we included the +optional marker.  However,
	// It is included in the serialized output even if empty. When omitted, the
	// default value is zero (the default for the int type).
	// +optional
	OptionalField2 int `json:"optionalField2"`

	// This field is optional since we included the omitempty marker.  It is
	// also not be included in the serialized output if empty. When omitted, the
	// default value is zero (the default for the int type).
	OptionalField3 int `json:"optionalField3,omitempty"`

	// This field is optional since we included the +optional and omitempty
	// markers.  It is not be included in the serialized output if empty because
	// we inluded omitempty.  Best practice is to use both markers together.
	// When omitted, the default value is nil (the default for pointers). It is
	// useful to use a pointer type when you want to distinguish between a field
	// that is not set and a field that is set to the default value.
	// +optional
	OptionalField4 *int `json:"optionalField4,omitempty"`

	// This field is optional since we included the +optional marker.
	// Apparently becuase it's a pointer field, it's omitted from the serialized
	// output even though we don't have omitempty. When omitted, the default
	// value is nil (the default for pointers). It is useful to use a pointer
	// type when you want to distinguish between a field that is not set and a
	// field that is set to the default value.
	// +optional
	OptionalField5 *int `json:"optionalField5"`

	// This field is optional since we included the omitempty marker.  It is
	// also not be included in the serialized output if empty. When omitted, the
	// default value is nil (the default for pointers). It is useful to use a
	// pointer type when you want to distinguish between a field that is not set
	// and a field that is set to the default value.
	OptionalField6 *int `json:"optionalField6,omitempty"`

	// This field is optional since we included the +optional marker.  It will
	// be included in the serialized output even if empty since we gave it a
	// default value.
	// +optional
	// +kubebuilder:default=42
	DefaultField int `json:"defaultField,omitempty"`

	// This field is required since we didn't make it optional.
	RequiredField1 int `json:"requiredField1"`

	// This field is required since we included the +required marker.
	// +required
	RequiredField2 int `json:"requiredField2"`

	// This field is required since we included the "validation:Required"
	// marker.
	// +kubebuilder:validation:Required
	RequiredField3 int `json:"requiredField3"`

	// You might think this field is required since we included the
	// "validation:Required" marker.  However, omitempty takes precedence,
	// making this field optional.
	// +kubebuilder:validation:Required
	NotReallyRequiredField1 int `json:"notReallyRequiredField1,omitempty"`
}