Fix DidUrl.toString() + test vectors

Author: filip26

src/main/java/com/apicatalog/did/DidUrl.java

@@ -137,25 +137,31 @@ public DidUrl asDidUrl() {
     public String toString() {
         final StringBuilder builder = new StringBuilder(super.toString());
 
-        if (Did.isNotBlank(path)) {
-            if (path.charAt(0) != '/') {
+        if (path != null) {
+            if (path.length() == 0 || path.charAt(0) != '/') {
                 builder.append('/');
             }
-            builder.append(path);
+            if (path.length() > 0) {
+                builder.append(path);
+            }
         }
 
-        if (Did.isNotBlank(query)) {
-            if (query.charAt(0) != '?') {
+        if (query != null) {
+            if (query.length() == 0 || query.charAt(0) != '?') {
                 builder.append('?');
             }
-            builder.append(query);
+            if (query.length() > 0) {
+                builder.append(query);                
+            }
         }
 
-        if (Did.isNotBlank(fragment)) {
-            if (fragment.charAt(0) != '#') {
+        if (fragment != null) {
+            if (fragment.length() == 0 || fragment.charAt(0) != '#') {
                 builder.append('#');
             }
-            builder.append(fragment);
+            if (fragment.length() > 0) {
+                builder.append(fragment);
+            }
         }
 
         return builder.toString();

src/test/java/com/apicatalog/did/DidUrlTest.java

@@ -71,7 +71,7 @@ void stringIsDid(String uri) {
     void uriIsDid(String uri) {
         assertTrue(DidUrl.isDidUrl(URI.create(uri)));
     }
-    
+
     @DisplayName("toString()")
     @ParameterizedTest(name = "{0}")
     @MethodSource({ "validVectors" })
@@ -163,6 +163,22 @@ static Stream<String[]> validVectors() {
                         null,
                         null,
                         ""
+                },
+                {
+                        "did:example:a/",
+                        "example",
+                        "a",
+                        "/",
+                        null,
+                        null
+                },
+                {
+                        "did:example:a/?#",
+                        "example",
+                        "a",
+                        "/",
+                        "",
+                        ""
                 }
 
         });