Fix deprecation warnings on Java 9

Author: marcphilipp

junit-jupiter-engine/src/test/java/org/junit/jupiter/engine/execution/injection/sample/DoubleParameterResolver.java

@@ -28,8 +28,8 @@ public boolean supportsParameter(ParameterContext parameterContext, ExtensionCon
 	}
 
 	@Override
-	public Object resolveParameter(ParameterContext parameterContext, ExtensionContext extensionContext) {
-		return new Double(42.0);
+	public Double resolveParameter(ParameterContext parameterContext, ExtensionContext extensionContext) {
+		return 42.0;
 	}
 
 }

junit-jupiter-engine/src/test/java/org/junit/jupiter/engine/execution/injection/sample/LongParameterResolver.java

@@ -56,8 +56,8 @@ public boolean supportsParameter(ParameterContext parameterContext, ExtensionCon
 	}
 
 	@Override
-	public Object resolveParameter(ParameterContext parameterContext, ExtensionContext extensionContext) {
-		return Long.valueOf(42);
+	public Long resolveParameter(ParameterContext parameterContext, ExtensionContext extensionContext) {
+		return 42L;
 	}
 
 }