Add /paper dumplisteners command

paper-api/src/main/java/com/destroystokyo/paper/event/executor/MethodHandleEventExecutor.java

@@ -18,10 +18,12 @@ public class MethodHandleEventExecutor implements EventExecutor {
 
     private final Class<? extends Event> eventClass;
     private final MethodHandle handle;
+    private final @Nullable Method method;
 
     public MethodHandleEventExecutor(final Class<? extends Event> eventClass, final MethodHandle handle) {
         this.eventClass = eventClass;
         this.handle = handle;
+        this.method = null;
     }
 
     public MethodHandleEventExecutor(final Class<? extends Event> eventClass, final Method m) {
@@ -32,6 +34,7 @@ public class MethodHandleEventExecutor implements EventExecutor {
         } catch (final IllegalAccessException e) {
             throw new AssertionError("Unable to set accessible", e);
         }
+        this.method = m;
     }
 
     @Override
@@ -43,4 +46,9 @@ public class MethodHandleEventExecutor implements EventExecutor {
             SneakyThrow.sneaky(t);
         }
     }
+
+    @Override
+    public String toString() {
+        return "MethodHandleEventExecutor['" + this.method + "']";
+    }
 }

paper-api/src/main/java/com/destroystokyo/paper/event/executor/StaticMethodHandleEventExecutor.java

@@ -19,6 +19,7 @@ public class StaticMethodHandleEventExecutor implements EventExecutor {
 
     private final Class<? extends Event> eventClass;
     private final MethodHandle handle;
+    private final Method method;
 
     public StaticMethodHandleEventExecutor(final Class<? extends Event> eventClass, final Method m) {
         Preconditions.checkArgument(Modifier.isStatic(m.getModifiers()), "Not a static method: %s", m);
@@ -30,6 +31,7 @@ public class StaticMethodHandleEventExecutor implements EventExecutor {
         } catch (final IllegalAccessException e) {
             throw new AssertionError("Unable to set accessible", e);
         }
+        this.method = m;
     }
 
     @Override
@@ -41,4 +43,9 @@ public class StaticMethodHandleEventExecutor implements EventExecutor {
             SneakyThrow.sneaky(throwable);
         }
     }
+
+    @Override
+    public String toString() {
+        return "StaticMethodHandleEventExecutor['" + this.method + "']";
+    }
 }