avoid calling getClass().getSimpleName() repeatedly

Surprisingly when I tested this locally, the JVM did not optimize it and lost some performance just for this statement. The value of using `getSimpleName()` here is not that great, so I simply hard-coded the value (I thought about making it a constant, but then went for simplicity, since the probability that this class will change and we overlook this renaming and it will actually cause a real problem / confusion is IMHO not that great).

Signed-off-by: Peter Gafert <peter.gafert@tngtech.com>

archunit/src/main/java/com/tngtech/archunit/core/importer/Location.java

@@ -140,9 +140,9 @@ private String encodeIllegalCharacters(String relativeURI) {
     }
 
     void checkScheme(String scheme, NormalizedUri uri) {
-        checkArgument(scheme.equals(uri.getScheme()),
-                "URI %s of %s must have scheme %s, but has %s",
-                uri, getClass().getSimpleName(), scheme, uri.getScheme());
+        String actualScheme = uri.getScheme();
+        checkArgument(scheme.equals(actualScheme),
+                "URI %s of Location must have scheme %s, but has %s", uri, scheme, actualScheme);
     }
 
     /**