Revert "Removal (temporary?) of substitution preventing logback working"

This reverts commit 11d9d6b.

Author: sdeleuze

spring-native/src/main/java/org/springframework/nativex/substitutions/logback/Target_ContextInitializer.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2019-2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.nativex.substitutions.logback;
+
+import java.net.URL;
+
+import ch.qos.logback.classic.LoggerContext;
+import ch.qos.logback.core.LogbackException;
+import ch.qos.logback.core.joran.spi.JoranException;
+import com.oracle.svm.core.annotate.Alias;
+import com.oracle.svm.core.annotate.Substitute;
+import com.oracle.svm.core.annotate.TargetClass;
+
+import org.springframework.nativex.substitutions.LogbackIsAround;
+import org.springframework.nativex.substitutions.OnlyIfPresent;
+
+@TargetClass(className = "ch.qos.logback.classic.util.ContextInitializer", onlyWith = { OnlyIfPresent.class, LogbackIsAround.class })
+final class Target_ContextInitializer {
+
+	@Alias
+	LoggerContext loggerContext;
+
+	@Substitute
+	public void configureByResource(URL url) throws JoranException {
+		if (url == null) {
+			throw new IllegalArgumentException("URL argument cannot be null");
+		}
+		final String urlString = url.toString();
+		if (urlString.endsWith("groovy")) {
+			throw new LogbackException("Logback Groovy configuration is not supported on native");
+		} else if (urlString.endsWith("xml")) {
+			throw new LogbackException("Logback XML configuration is not supported yet, see https://github.com/spring-projects-experimental/spring-native/issues/625");
+		}
+	}
+}