func (this *URIImpl) IsSipURI() bool {
	var uri URI = this
	_, ok := uri.(SipURI)
	return ok
}
This method determines if this is a URI with a scheme of
"sip" or "sips".

@return true if the scheme is "sip" or "sips", false otherwise.
package address
import (
	"strings"
)
type URIImpl struct {
	uriString string
	scheme string
}
func NewURIImpl(uriString string) *URIImpl {
	i := strings.Index(uriString, ":")
	if i > 0 {
		return &URIImpl{uriString: uriString, scheme: uriString[0:i]}
	}
	return nil
}
func (this *URIImpl) String() string {
	return this.uriString
}
func (this *URIImpl) Clone() interface{} {
	return NewURIImpl(this.uriString)
}
func (this *URIImpl) GetScheme() string {
	return this.scheme
}