Clarify comment on escaped null string in tests

Updated comment for clarity on null string handling.

Author: garydgregory

src/test/java/org/apache/commons/csv/CSVParserTest.java

@@ -587,7 +587,7 @@ void testEndOfFileBehaviorExcel() throws Exception {
     @ParameterizedTest
     @EnumSource(value = CSVFormat.Predefined.class, names = { "MySQL", "PostgreSQLCsv", "PostgreSQLText", "Oracle" })
     void testEscapedNullStringIsAValue(final CSVFormat.Predefined predefined) throws Exception {
-        // For formats whose null string is "\\N" (e.g., MySQL, PostgreSQL Text, Oracle), 
+        // For formats whose null string is "\\N" (e.g., MySQL, PostgreSQL Text, Oracle),
         // a literal value "\\N" must be written as "\\\\N" so it is not read back as null.
         final CSVFormat format = predefined.getFormat();
         final StringWriter writer = new StringWriter();