Polish "Avoid using deprecated Log4J constructors"

See gh-46372

Author: snicoll

core/spring-boot/src/main/java/org/springframework/boot/logging/log4j2/ExtendedWhitespaceThrowablePatternConverter.java

@@ -38,15 +38,15 @@
 @ConverterKeys({ "xwEx", "xwThrowable", "xwException" })
 public final class ExtendedWhitespaceThrowablePatternConverter extends LogEventPatternConverter {
 
-	private final LogEventPatternConverter delegate;
+	private final ExtendedThrowablePatternConverter delegate;
 
 	private final String separator;
 
 	@SuppressWarnings("deprecation") // https://github.com/apache/logging-log4j2/issues/3809
 	private ExtendedWhitespaceThrowablePatternConverter(Configuration configuration, @Nullable String[] options) {
 		super("WhitespaceExtendedThrowable", "throwable");
 		this.delegate = ExtendedThrowablePatternConverter.newInstance(configuration, options);
-		this.separator = ((ExtendedThrowablePatternConverter) this.delegate).getOptions().getSeparator();
+		this.separator = this.delegate.getOptions().getSeparator();
 	}
 
 	@Override

core/spring-boot/src/main/java/org/springframework/boot/logging/log4j2/WhitespaceThrowablePatternConverter.java

@@ -37,15 +37,15 @@
 @ConverterKeys({ "wEx", "wThrowable", "wException" })
 public final class WhitespaceThrowablePatternConverter extends LogEventPatternConverter {
 
-	private final LogEventPatternConverter delegate;
+	private final ExtendedThrowablePatternConverter delegate;
 
 	private final String separator;
 
 	@SuppressWarnings("deprecation") // https://github.com/apache/logging-log4j2/issues/3809
 	private WhitespaceThrowablePatternConverter(Configuration configuration, @Nullable String[] options) {
 		super("WhitespaceThrowable", "throwable");
 		this.delegate = ExtendedThrowablePatternConverter.newInstance(configuration, options);
-		this.separator = ((ExtendedThrowablePatternConverter) this.delegate).getOptions().getSeparator();
+		this.separator = this.delegate.getOptions().getSeparator();
 	}
 
 	@Override