Fix code formatting issues in OfflineCauseTest

Remove extra blank lines and trailing spaces to satisfy Spotless checks.

Author: MinuteHanD

core/src/test/java/hudson/slaves/OfflineCauseTest.java

@@ -22,18 +22,18 @@ void testChannelTermination_NoStacktrace() {
     @ExportedBean
     public static class ExportableException extends Exception {
         private final String testMessage;
-        
+
         public ExportableException(String message) {
             super(message);
             this.testMessage = message;
         }
-        
+
         @Exported
         public String getTestMessage() {
             return testMessage;
         }
     }
-    
+
     public static class NonExportableException extends Exception {
         public NonExportableException(String message) {
             super(message);
@@ -44,7 +44,7 @@ public NonExportableException(String message) {
     void testChannelTermination_ExportsCauseWhenExportedBean() {
         ExportableException exportableException = new ExportableException("test message");
         OfflineCause.ChannelTermination termination = new OfflineCause.ChannelTermination(exportableException);
-        
+
         // The getCause() method should return the exception when it's an ExportedBean
         assertThat(termination.getCause(), sameInstance(exportableException));
     }
@@ -53,16 +53,16 @@ void testChannelTermination_ExportsCauseWhenExportedBean() {
     void testChannelTermination_DoesNotExportNonExportableException() {
         NonExportableException nonExportableException = new NonExportableException("test message");
         OfflineCause.ChannelTermination termination = new OfflineCause.ChannelTermination(nonExportableException);
-        
+
         // The getCause() method should return null when the exception is not an ExportedBean
         assertThat(termination.getCause(), nullValue());
     }
 
     @Test
     void testChannelTermination_HandlesNullCause() {
         OfflineCause.ChannelTermination termination = new OfflineCause.ChannelTermination(null);
-        
-        // The getCause() method should handle null cause 
+
+        // The getCause() method should handle null cause
         assertThat(termination.getCause(), nullValue());
     }