public void test_setDefaultValue() {
        fileTypeHelper.setDefaultValue("unknown");
        assertEquals("unknown", fileTypeHelper.getDefaultValue());

        // Test that get() returns new default value
        assertEquals("unknown", fileTypeHelper.get("non/existent"));
    }

    public void test_setDefaultValue_withNull() {
        fileTypeHelper.setDefaultValue(null);
        assertNull(fileTypeHelper.getDefaultValue());

    }

    /**
     * Sets the default file type value to use when MIME type is not found.
     *
     * @param defaultValue the new default file type value
     */
    public void setDefaultValue(final String defaultValue) {
        this.defaultValue = defaultValue;
    }

    /**
     * Gets all distinct file types currently configured in the mappings.
     *