Remove usage of StringBuilder as it's unneeded

There are no advantages here, only disadvantages.

Author: goncalossilva

src/main/java/com/fasterxml/jackson/core/Version.java

@@ -76,13 +76,7 @@ public Version(int major, int minor, int patchLevel, String snapshotInfo,
     public String getArtifactId() { return _artifactId; }
 
     public String toFullString() {
-        return new StringBuilder()
-        	.append(_groupId)
-        	.append('/')
-        	.append(_artifactId)
-        	.append('/')
-        	.append(toString())
-        	.toString();
+        return _groupId + '/' + _artifactId + '/' + toString();
     }
 
     @Override