Polish 'Remove ResourceUtils.getURL logging config check'

Extend `initializeSystem` to search the exception stack for a
FileNotFoundException before reporting the error. This allows
us to provide a similar stack trace to the one that used to be
thrown when we had the `ResourceUtils.getURL` check.

See gh-22946

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/logging/LoggingApplicationListener.java

 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 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.
@@ -16,6 +16,7 @@
 
 package org.springframework.boot.context.logging;
 
+import java.io.FileNotFoundException;
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
@@ -316,9 +317,14 @@ public class LoggingApplicationListener implements GenericApplicationListener {
 				system.initialize(initializationContext, logConfig, logFile);
 			}
 			catch (Exception ex) {
+				Throwable exceptionToReport = ex;
+				while (exceptionToReport != null && !(exceptionToReport instanceof FileNotFoundException)) {
+					exceptionToReport = exceptionToReport.getCause();
+				}
+				exceptionToReport = (exceptionToReport != null) ? exceptionToReport : ex;
 				// NOTE: We can't use the logger here to report the problem
 				System.err.println("Logging system failed to initialize using configuration from '" + logConfig + "'");
-				ex.printStackTrace(System.err);
+				exceptionToReport.printStackTrace(System.err);
 				throw new IllegalStateException(ex);
 			}
 		}

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/logging/LoggingApplicationListenerTests.java

 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 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.
@@ -165,9 +165,10 @@ class LoggingApplicationListenerTests {
 		addPropertiesToEnvironment(this.context, "logging.config=doesnotexist.xml");
 		assertThatIllegalStateException().isThrownBy(() -> {
 			this.initializer.initialize(this.context.getEnvironment(), this.context.getClassLoader());
-			assertThat(this.output)
-					.contains("Logging system failed to initialize using configuration from 'doesnotexist.xml'");
 		});
+		assertThat(this.output)
+				.contains("Logging system failed to initialize using configuration from 'doesnotexist.xml'")
+				.doesNotContain("JoranException");
 	}
 
 	@Test