public void visitSignature(SignatureVisitor visitor) {
        if (wildcard) {
            visitor.visitText("?");
        } else if (upperBounds != null) {
            visitor.visitText("? extends ");
            upperBounds.visitSignature(visitor);
        } else if (lowerBounds != null) {
            visitor.visitText("? super ");
            lowerBounds.visitSignature(visitor);
        } else {

        type.visitSignature(visitor)

        then:
        1 * visitor.visitType('org.gradle.SomeType')
        1 * visitor.visitText('<')
        1 * visitor.visitType('OtherType')
        1 * visitor.visitText('>')
        0 * visitor._
    }

    def visitsSignatureForWildcardType() {
        TypeMetaData.SignatureVisitor visitor = Mock()
        type.setWildcard()

        when:

        final Element linkElement = document.createElement("classname");

        type.visitSignature(new TypeMetaData.SignatureVisitor() {
            @Override
            public void visitText(String text) {
                linkElement.appendChild(document.createTextNode(text));
            }

            @Override
            public void visitType(String name) {

     *
     * <p>For example, if horizon is {@code [[a, b], [c, d], [e]]}, {@code visitNext()} will return
     * {@code [a, b, null, c, d, null, e, null]} sequentially, encoding the topological structure.
     * (Note, however, that the callers of {@code visitNext()} often insert additional iterators
     * into {@code horizon} between calls to {@code visitNext()}. This causes them to receive
     * additional values interleaved with those shown above.)