Add overloaded getValue method to ModalInteractionEvent

[lajczik]

Currently, ModalInteractionEvent#getValue(String id) can return null, which forces developers to perform manual null checks before accessing modal values.

I propose adding an overloaded version of getValue - inspired by SlashCommandInteractionEvent#getOption(...) - that allows specifying a fallback value and a mapping function for cleaner and safer access.

Proposed Method

@Nullable
default <T> T getValue(@NotNull String id, @Nullable T fallback, @NotNull Function<ModalMapping, T> mapper) {
    ModalMapping mapping = getValue(id);
    return mapping != null ? mapper.apply(mapping) : fallback;
}

Example Usage (new way)

@Override
public void onModalInteraction(ModalInteractionEvent e) {
    String input = e.getValue("customid", "fallback string", ModalMapping::getAsString);
    e.reply("Received: " + input).queue();
}

Current Usage (for comparison)

@Override
public void onModalInteraction(ModalInteractionEvent e) {
    ModalMapping mapping = e.getValue("customid");
    String input = mapping != null ? mapping.getAsString() : "fallback string";
    e.reply("Received: " + input).queue();
}

Inspiration

This idea is directly inspired by the getOption(String name, T defaultValue, Function<OptionMapping, T> mapper) method in SlashCommandInteractionEvent, which provides a consistent and null-safe way to retrieve data from slash commands.

Benefits

• Removes the need for repetitive null checks.
• Improves API consistency across interaction types.
• Enables cleaner, more functional-style code.
• Makes migration between slash commands and modals easier.

[MinnDevelopment]

The problem with this is that an unfilled TextInput field in a modal results in an empty value rather than a missing value. This means your fallback that only checks for null does not do anything. The getValue(customId) only returns null if the original modal didn't have any component with that customId in it, is that a use-case you run into?