[Bleeding] Added Conversations API. Addresses BUKKIT-864

By: rmichela <deltahat@gmail.com>

paper-api/src/main/java/org/bukkit/conversations/BooleanPrompt.java

@@ -0,0 +1,33 @@
+package org.bukkit.conversations;
+
+import org.apache.commons.lang.ArrayUtils;
+import org.apache.commons.lang.BooleanUtils;
+
+/**
+ * BooleanPrompt is the base class for any prompt that requires a boolean response from the user.
+ */
+public abstract class BooleanPrompt extends ValidatingPrompt{
+
+    public BooleanPrompt() {
+        super();
+    }
+
+    @Override
+    protected boolean isInputValid(ConversationContext context, String input) {
+        String[] accepted = {"true", "false", "on", "off", "yes", "no"};
+        return ArrayUtils.contains(accepted, input.toLowerCase());
+    }
+
+    @Override
+    protected Prompt acceptValidatedInput(ConversationContext context, String input) {
+        return acceptValidatedInput(context, BooleanUtils.toBoolean(input));
+    }
+
+    /**
+     * Override this method to perform some action with the user's boolean response.
+     * @param context Context information about the conversation.
+     * @param input The user's boolean response.
+     * @return The next {@link Prompt} in the prompt graph.
+     */
+    protected abstract Prompt acceptValidatedInput(ConversationContext context, boolean input);
+}