NULL characters appearing in CouchDB when using composite keys about cckit HOT 2 CLOSED

        // CreateCompositeKey combines the given `attributes` to form a composite
	// key. The objectType and attributes are expected to have only valid utf8
	// strings and should not contain U+0000 (nil byte) and U+10FFFF
	// (biggest and unallocated code point).
	// The resulting composite key can be used as the key in PutState().
	CreateCompositeKey(objectType string, attributes []string) (string, error)

const (
	minUnicodeRuneValue   = 0            //U+0000
	maxUnicodeRuneValue   = utf8.MaxRune //U+10FFFF - maximum (and unallocated) code point
	compositeKeyNamespace = "\x00"
	emptyKeySubstitute    = "\x01"
)