solution

type Components struct {
	Systemd api.Systemd `yaml:"systemd,omitempty"`
	Helm    *api.Helm   `yaml:"helm,omitempty"`
}

type CorePlatform struct {
	Image string `yaml:"image" validate:"required"`
}

type ReleaseManifest struct {
	Schema       api.SchemaVersion `yaml:"schema,omitempty"`
	Metadata     *api.Metadata     `yaml:"metadata,omitempty"`
	CorePlatform *CorePlatform     `yaml:"corePlatform" validate:"required"`
	Components   Components        `yaml:"components,omitempty"`
}