public static String[] toStringArray(Collection<String> collection) {
        if (collection == null) {
            return null;
        }
        return collection.toArray(EMPTY_STRING_ARRAY);
    }
Copy the given {@code Collection} into a {@code String} array.
<p>The {@code Collection} must contain {@code String} elements only.
@param collection the {@code Collection} to copy
@return the {@code String} array ({@code null} if the supplied
{@code Collection} was {@code null})
agent-module/bootstraps/bootstrap-core/src/main/java/com/navercorp/pinpoint/bootstrap/util/spring/StringUtils.java