Stop URLs on ` (grave accent, backtick) as well

It's not a valid URI character according to RFC 3986 and the URL
Standard lists them as part of the percent-encoded set, same as space,
", < and >.

Author: robinst

src/main/java/org/nibor/autolink/internal/Scanners.java

@@ -61,10 +61,13 @@ public static int findUrlEnd(CharSequence input, int beginIndex) {
                 case '\u001D':
                 case '\u001E':
                 case '\u001F':
+                // These are part of "fragment percent-encode set" which means they need to be
+                // percent-encoded in an URL: https://url.spec.whatwg.org/#fragment-percent-encode-set
                 case ' ':
                 case '\"':
                 case '<':
                 case '>':
+                case '`':
                 case '\u007F':
                 case '\u0080':
                 case '\u0081':
@@ -100,7 +103,7 @@ public static int findUrlEnd(CharSequence input, int beginIndex) {
                 case '\u009F':
                     // The above can never be part of an URL, so stop now. See RFC 3986 and RFC 3987.
                     // Some characters are not in the above list, even they are not in "unreserved" or "reserved":
-                    //   '\\', '^', '`', '{', '|', '}'
+                    //   '\\', '^', '{', '|', '}'
                     // The reason for this is that other link detectors also allow them. Also see below, we require
                     // the braces to be balanced.
                 case '\u00A0': // no-break space

src/test/java/org/nibor/autolink/AutolinkUrlTest.java

@@ -153,6 +153,9 @@ public void quotes() {
         // " not allowed in URLs
         assertLinked("http://example.org/\"a", "|http://example.org/|\"a");
         assertLinked("http://example.org/\"a\"", "|http://example.org/|\"a\"");
+        // ` not allowed in URLs
+        assertLinked("http://example.org/`a", "|http://example.org/|`a");
+        assertLinked("http://example.org/`a`", "|http://example.org/|`a`");
     }
 
     @Test