make ArchConditions.createMessage(..) available as public API

This convenience method also helps users to create standard ArchUnit violation messages, so we offer it as public API. Since we meanwhile have a Java 8 source level we can even put this method into `ConditionEvent` where it fits better.

Signed-off-by: Peter Gafert <[email protected]>

archunit/src/main/java/com/tngtech/archunit/lang/ConditionEvent.java

@@ -19,7 +19,10 @@
 import java.util.List;
 
 import com.tngtech.archunit.PublicAPI;
+import com.tngtech.archunit.base.HasDescription;
+import com.tngtech.archunit.core.domain.JavaClass;
 import com.tngtech.archunit.core.domain.JavaMethodCall;
+import com.tngtech.archunit.core.domain.properties.HasSourceCodeLocation;
 
 import static com.tngtech.archunit.PublicAPI.State.EXPERIMENTAL;
 import static com.tngtech.archunit.PublicAPI.Usage.ACCESS;
@@ -66,6 +69,21 @@ public interface ConditionEvent {
     @PublicAPI(usage = INHERITANCE, state = EXPERIMENTAL)
     void handleWith(Handler handler);
 
+    /**
+     * Convenience method to create a standard ArchUnit {@link ConditionEvent} message. It will prepend the
+     * description of the object that caused the event (e.g. a {@link JavaClass}) and append the source code
+     * location of the respective object.
+     *
+     * @param object The object to describe, e.g. the {@link JavaClass} {@code com.example.SomeClass}
+     * @param message The message that should be filled into the template, e.g. "does not have simple name 'Correct'"
+     * @return The formatted message, e.g. {@code Class <com.example.SomeClass> does not have simple name 'Correct' in (SomeClass.java:0)}
+     * @param <T> The object described by the event.
+     */
+    @PublicAPI(usage = ACCESS)
+    static <T extends HasDescription & HasSourceCodeLocation> String createMessage(T object, String message) {
+        return object.getDescription() + " " + message + " in " + object.getSourceCodeLocation();
+    }
+
     /**
      * Handles the data of a {@link ConditionEvent} that is the corresponding objects and the description
      * (compare {@link #handleWith(Handler)}).<br>

archunit/src/main/java/com/tngtech/archunit/lang/conditions/ArchConditions.java

@@ -117,6 +117,7 @@
 import static com.tngtech.archunit.core.domain.properties.HasReturnType.Predicates.rawReturnType;
 import static com.tngtech.archunit.core.domain.properties.HasThrowsClause.Predicates.throwsClauseContainingType;
 import static com.tngtech.archunit.core.domain.properties.HasType.Predicates.rawType;
+import static com.tngtech.archunit.lang.ConditionEvent.createMessage;
 import static com.tngtech.archunit.lang.conditions.ArchPredicates.have;
 import static java.util.Arrays.asList;
 
@@ -1284,10 +1285,6 @@ public static ArchCondition<JavaCodeUnit> onlyBeCalledByConstructorsThat(Describ
                 origin.is(constructor().and(predicate)), GET_CALLS_OF_SELF);
     }
 
-    private static <T extends HasDescription & HasSourceCodeLocation> String createMessage(T object, String message) {
-        return object.getDescription() + " " + message + " in " + object.getSourceCodeLocation();
-    }
-
     private static final IsConditionByPredicate<JavaClass> BE_TOP_LEVEL_CLASSES =
             new IsConditionByPredicate<>("a top level class", JavaClass.Predicates.TOP_LEVEL_CLASSES);
     private static final IsConditionByPredicate<JavaClass> BE_NESTED_CLASSES =