private List<MimeType> applyHint(List<MimeType> possibleTypes, MimeType hint) {
        if (possibleTypes == null || possibleTypes.isEmpty()) {
            return Collections.singletonList(hint);
        } else {
            for (final MimeType type : possibleTypes) {
                if (hint.equals(type) ||
                        registry.isSpecializationOf(hint.getType(), type.getType())) {
                    // Use just this type
                    return Collections.singletonList(hint);
                }
            }
        }

        // Hint didn't help, sorry
        return possibleTypes;
    }
Use the MimeType hint to try to clarify or specialise the current
possible types list.
If the hint is a specialised form, use that instead
If there are multiple possible types, use the hint to select one
tika-core/src/main/java/org/apache/tika/mime/MimeTypes.java