liquibase-core/src/main/java/liquibase/util/file/FilenameUtils.java
public static boolean isExtension(String filename, Collection extensions) {
        if (filename == null) {
            return false;
        }
        if ((extensions == null) || extensions.isEmpty()) {
            return (indexOfExtension(filename) == -1);
        }
        String fileExt = getExtension(filename);
        for (Iterator it = extensions.iterator(); it.hasNext();) {
            if (fileExt.equals(it.next())) {
                return true;
            }
        }
        return false;
    }
public static boolean isExtension(String filename, Collection extensions) {
        if (filename == null) {
            return false;
        }
        if ((extensions == null) || extensions.isEmpty()) {
            return (indexOfExtension(filename) == -1);
        }
        String fileExt = getExtension(filename);
        for (Iterator it = extensions.iterator(); it.hasNext();) {
            if (fileExt.equals(it.next())) {
                return true;
            }
        }
        return false;
    }
Checks whether the extension of the filename is one of those specified.
<p>
This method obtains the extension as the textual part of the filename
after the last dot. There must be no directory separator after the dot.
The extension check is case-sensitive on all platforms.

@param filename  the filename to query, null returns false
@param extensions  the extensions to check for, null checks for no extension
@return true if the filename is one of the extensions