Fix checkstyle: Split long line

Author: aherbert

src/main/java/org/apache/commons/csv/CSVParser.java

@@ -501,7 +501,8 @@ private Headers createHeaders() throws IOException {
                         if (!emptyHeader && !this.format.getAllowDuplicateHeaderNames()) {
                             throw new IllegalArgumentException(
                                 String.format(
-                                    "The header contains a duplicate name: \"%s\" in %s. If this is valid then use CSVFormat.withAllowDuplicateHeaderNames().",
+                                    "The header contains a duplicate name: \"%s\" in %s. " +
+                                    "If this is valid then use CSVFormat.withAllowDuplicateHeaderNames().",
                                     header, Arrays.toString(headerRecord)));
                         }
                         if (emptyHeader && !this.format.getAllowMissingColumnNames()) {