src/main/java/net/wasdev/wlp/common/plugins/util/InstallFeatureUtil.java
private Set<String> getConfigDropinsFeatures(Set<String> origResult, File serverDirectory, String folderName) {
        Set<String> result = origResult;
        File configDropinsFolder;
        try {
            configDropinsFolder = new File(new File(serverDirectory, "configDropins"), folderName).getCanonicalFile();
        } catch (IOException e) {
            // skip this directory if its path cannot be queried
            warn("The " + serverDirectory + "/configDropins/" + folderName + " directory cannot be accessed. Skipping its server features.");
            debug(e);
            return result;
        }
        File[] configDropinsXmls = configDropinsFolder.listFiles(new FilenameFilter() {
            @Override
            public boolean accept(File dir, String name) {
                return name.endsWith(".xml");
            }
        });
        if (configDropinsXmls == null || configDropinsXmls.length == 0) {
            return result;
        }
        // sort the files in alphabetical order so that overrides will happen in the proper order
        Comparator<File> comparator = new Comparator<File>() {
            @Override
            public int compare(File left, File right) {
                return left.getAbsolutePath().toLowerCase().compareTo(right.getAbsolutePath().toLowerCase());
            }
        };
        Collections.sort(Arrays.asList(configDropinsXmls), comparator);

        for (File xml : configDropinsXmls) {
            Set<String> features = getServerXmlFeatures(result, xml, null);
            if (features != null) {
                result = features;
            }
        }
        return result;
    }
private Set<String> getConfigDropinsFeatures(Set<String> origResult, File serverDirectory, String folderName) {
        Set<String> result = origResult;
        File configDropinsFolder;
        try {
            configDropinsFolder = new File(new File(serverDirectory, "configDropins"), folderName).getCanonicalFile();
        } catch (IOException e) {
            // skip this directory if its path cannot be queried
            warn("The " + serverDirectory + "/configDropins/" + folderName + " directory cannot be accessed. Skipping its server features.");
            debug(e);
            return result;
        }
        File[] configDropinsXmls = configDropinsFolder.listFiles(new FilenameFilter() {
            @Override
            public boolean accept(File dir, String name) {
                return name.endsWith(".xml");
            }
        });
        if (configDropinsXmls == null || configDropinsXmls.length == 0) {
            return result;
        }
        // sort the files in alphabetical order so that overrides will happen in the proper order
        Comparator<File> comparator = new Comparator<File>() {
            @Override
            public int compare(File left, File right) {
                return left.getAbsolutePath().toLowerCase().compareTo(right.getAbsolutePath().toLowerCase());
            }
        };
        Collections.sort(Arrays.asList(configDropinsXmls), comparator);

        for (File xml : configDropinsXmls) {
            Set<String> features = getServerXmlFeatures(result, xml, null);
            if (features != null) {
                result = features;
            }
        }
        return result;
    }
Gets features from the configDropins's defaults or overrides directory

@param origResult
The features that have been parsed so far.
@param serverDirectory
The server directory
@param folderName
The folder under configDropins: either "defaults" or
"overrides"
@return The set of features to install, or empty set if the cumulatively
parsed xml files only have featureManager sections but no
features to install, or null if there are no valid xml files or
they have no featureManager section