in src/main/java/org/apache/sling/javax/activation/internal/OsgiMailcapCommandMap.java [218:238]
    private DataContentHandler findDataContentHandler(String mimeType, boolean fallback) {
        for (Map.Entry<Bundle, MailcapFile> entry : db.entrySet()) {
            Map<?, ?> commandMap = fallback ? entry.getValue().getMailcapFallbackList(mimeType) : entry.getValue()
                    .getMailcapList(mimeType);
            if (commandMap != null) {
                List<?> v = (List<?>) commandMap.get("content-handler");
                if (v == null) {
                    continue;
                }
                String name = (String) v.get(0);
                DataContentHandler dch = getDataContentHandler(name, entry.getKey());
                if (dch != null) {
                    return dch;
                }
            }
        }
        return null;
    }