Improve speed and memory use of FixedMetadataValue. Fixes BUKKIT-1460

FixedMetadataValue currently just extends LazyMetadataValue with a value
that never changes. While this works it is a lot of unneeded overhead
that causes FixedMetadataValue to be a lot slower and use a lot more
memory than one would expect. To correct this we store the value directly
in FixedMetadataValue and override the the appropriate methods to use it.

Ideally we would modify FixedMetadataValue to no longer extend
LazyMetadataValue as this would give a very large memory savings. However,
this is not currently done for backwards compatibility reasons.

By: crast <contact@jamescrasta.com>

paper-api/src/test/java/org/bukkit/metadata/FixedMetadataValueTest.java

@@ -1,6 +1,7 @@
 package org.bukkit.metadata;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertSame;
 
 import org.bukkit.plugin.Plugin;
 import org.bukkit.plugin.TestPlugin;
@@ -10,21 +11,32 @@ public class FixedMetadataValueTest {
     private Plugin plugin = new TestPlugin("X");
     private FixedMetadataValue subject;
 
-    private void valueEquals(Object value) {
-        subject = new FixedMetadataValue(plugin, value);
-        assertEquals(value, subject.value());
+    @Test
+    public void testBasic() {
+        subject = new FixedMetadataValue(plugin, new Integer(50));
+        assertSame(plugin, subject.getOwningPlugin());
+        assertEquals(new Integer(50), subject.value());
     }
 
     @Test
-    public void testTypes() {
-        valueEquals(10);
-        valueEquals(0.1);
-        valueEquals("TEN");
-        valueEquals(true);
-        valueEquals(null);
-        valueEquals((float) 10.5);
-        valueEquals((long) 10);
-        valueEquals((short) 10);
-        valueEquals((byte) 10);
+    public void testNumberTypes() {
+        subject = new FixedMetadataValue(plugin, new Integer(5));
+        assertEquals(new Integer(5), subject.value());
+        assertEquals(5, subject.asInt());
+        assertEquals(true, subject.asBoolean());
+        assertEquals(5, subject.asByte());
+        assertEquals(5.0, subject.asFloat(), 0.1e-8);
+        assertEquals(5.0D, subject.asDouble(), 0.1e-8D);
+        assertEquals(5L, subject.asLong());
+        assertEquals(5, subject.asShort());
+        assertEquals("5", subject.asString());
+    }
+
+    @Test
+    public void testInvalidateDoesNothing() {
+        Object o = new Object();
+        subject = new FixedMetadataValue(plugin, o);
+        subject.invalidate();
+        assertSame(o, subject.value());
     }
 }