Made combine more consistent for all numeric types

For all boxed primitive numeric types, combine now adds them instead of just integers

src/main/java/com/mojang/brigadier/results/CommandResult.java

@@ -18,22 +18,48 @@ public interface CommandResult {
  * @return The combined result
  */
  default Object combine(Object other) {
- ListCommandResult list = new ListCommandResult();
- list.combine(this);
- list.combine(other);
- return list;
+ return ListCommandResult.from(this, other);
  }
 
+ /**
+ * <p>Combine any objects, even if they are not Command Results.
+ * Target is the object which will be mutated to contain
+ * the combined target and source.
+ * 
+ * <p>If either of the supplied objects are EmptyCommandResult, the
+ * non-empty result will be returned.
+ * 
+ * <p>If the target implements CommandResult, the `combine` method
+ * will be called on the target: `target.combine(source)`
+ * 
+ * <p>If the target and source are the same type of boxed primitive
+ * number (ie Integer, Long, Double, etc.), they will be added together.
+ * 
+ * <p>Otherwise, a new ListCommandResult containing both target and source
+ * will be returned.
+ * 
+ * @param target the object which the source will be combined into
+ * @param source the object to combine into the target
+ */
  static Object combine(Object target, Object source) {
  if (target instanceof CommandResult) {
  return ((CommandResult)target).combine(source);
- } else if (target instanceof Integer && source instanceof Integer) {
- // Backwards compatability
- return (Integer)target + (Integer)source;
  } else if (source instanceof EmptyCommandResult) {
  return target;
+ } else if (target instanceof Byte && source instanceof Byte) {
+ return (byte) target + (byte) source;
+ } else if (target instanceof Short && source instanceof Short) {
+ return (short) target + (short) source;
+ } else if (target instanceof Integer && source instanceof Integer) {
+ return (int) target + (int) source;
+ } else if (target instanceof Long && source instanceof Long) {
+ return (long) source + (long) source;
+ } else if (source instanceof Float && source instanceof Float) {
+ return (float) source + (float) source;
+ } else if (source instanceof Double && target instanceof Double) {
+ return (double) source + (double) target;
  } else {
- return source;
+ return ListCommandResult.from(target, source);
  }
  }
 }

src/main/java/com/mojang/brigadier/results/ListCommandResult.java

@@ -21,4 +21,11 @@ public ListCommandResult combine(Object other) {
 
  return this;
  }
+
+ public static ListCommandResult from(Object a, Object b) {
+ ListCommandResult list = new ListCommandResult();
+ list = list.combine(a);
+ list = list.combine(b);
+ return list;
+ }
 }