If you want to restrict to filenames that exactly match a given filename, you will need to use the regular expression (RegEx) syntax. This is done by prepending the "^" character (which matches the beginning of the name) and appending the "$" character (which matches the end of the name). So setting the "File/folder name restriction" to "^report$" will cause the directory listener to retrieve "report.txt", but not "test_report.txt" or "report_test.txt".
Also worth noting is that the filename restriction is case-sensitive by default. So a restriction of "report" will not match a file named "REPORT.txt". Again we can use the regular expression syntax to ignore case by including "(?i)" at the beginning. So for example, "(?i)^report$" would match "report.txt", "Report.txt" and "REPORT.txt".
The above are just a couple of examples of regular expressions. To learn more about regular expressions, do an internet search for "java regular expression tutorial".