ClusterSelectorAnnotationConflictError reports that an object has both the legacy cluster-selector annotation and the inline annotation.

EmptySelectorError reports that a ClusterSelector or NamespaceSelector is invalid because it is empty.

FilterClusters returns the list of Clusters in the passed array of FileObjects.

InvalidSelectorError reports that a ClusterSelector or NamespaceSelector is invalid.

ListNamespaceError reports a LIST namespace error when applying NamespaceSelectors.

ObjectHasUnknownClusterSelector reports that `resource`'s cluster-selector annotation references a ClusterSelector that does not exist.

ObjectHasUnknownNamespaceSelector reports that `resource`'s namespace-selector annotation references a NamespaceSelector that does not exist.

ObjectNotInNamespaceSelectorSubdirectory reports that `resource` is not in a subdirectory of the directory declaring `selector`.

UnknownNamespaceSelectorModeError reports that a NamespaceSelector mode is unknown.

UnsupportedNamespaceSelectorModeError reports that a NamespaceSelector uses the dynamic mode with the hierarchy source format.

ClusterSelectorAnnotationConflictErrorCode is the error code for ClusterSelectorAnnotationConflictError.

TODO: Must refactor to use properly.

ListNamespaceErrorCode is the error code for ListNamespaceError used in NamespaceSelector.

ObjectHasUnknownSelectorCode is the error code for ObjectHasUnknownClusterSelector.