static <C> @NonNull CaptionProvider<C> forCaption(
            final @NonNull Caption caption,
            final @NonNull Function<@NonNull C, @Nullable String> provider
    ) {
        return (key, recipient) -> {
            if (key.equals(caption)) {
                return provider.apply(recipient);
            }
            return null;
        };
    }
Returns a {@link CaptionProvider} that only returns values for the given {@code caption}, and returns
{@code null} for all other captions.

@param <C>      the command sender type
@param caption  the caption key
@param provider the provider of the value
@return the provider
cloud-core/src/main/java/org/incendo/cloud/caption/CaptionProvider.java