Add option to ignore the java version check in CB

Fixes GH-2935

Spigot-Server-Patches/0437-Allow-overriding-the-java-version-check.patch

@@ -0,0 +1,23 @@
+From 4747cf7910f84bd591445645e21568b9c3ae2e3d Mon Sep 17 00:00:00 2001
+From: Zach Brown <zach@zachbr.io>
+Date: Sat, 8 Feb 2020 18:02:24 -0600
+Subject: [PATCH] Allow overriding the java version check
+
+-DPaper.IgnoreJavaVersion=true
+
+diff --git a/src/main/java/org/bukkit/craftbukkit/Main.java b/src/main/java/org/bukkit/craftbukkit/Main.java
+index eb5f44e30..af05f3c1e 100644
+--- a/src/main/java/org/bukkit/craftbukkit/Main.java
++++ b/src/main/java/org/bukkit/craftbukkit/Main.java
+@@ -175,7 +175,7 @@ public class Main {
+             float javaVersion = Float.parseFloat(System.getProperty("java.class.version"));
+             if (javaVersion > 57.0) {
+                 System.err.println("Unsupported Java detected (" + javaVersion + "). Only up to Java 13 is supported.");
+-                return;
++                if (!Boolean.getBoolean("Paper.IgnoreJavaVersion")) return;
+             }
+ 
+             try {
+-- 
+2.25.0
+