#1002: Add Player Profile API

Slight changes may occur as this API is stabilized.

This PR is based on work previously done by DerFrZocker in #938.

By: blablubbabc <lukas@wirsindwir.de>

paper-server/src/main/java/org/bukkit/craftbukkit/configuration/ConfigSerializationUtil.java

@@ -0,0 +1,39 @@
+package org.bukkit.craftbukkit.configuration;
+
+import java.util.Map;
+import java.util.NoSuchElementException;
+import java.util.UUID;
+import org.bukkit.configuration.serialization.ConfigurationSerializable;
+
+/**
+ * Utilities related to the serialization and deserialization of {@link ConfigurationSerializable}s.
+ */
+public final class ConfigSerializationUtil {
+
+    public static String getString(Map<?, ?> map, String key, boolean nullable) {
+        return getObject(String.class, map, key, nullable);
+    }
+
+    public static UUID getUuid(Map<?, ?> map, String key, boolean nullable) {
+        String uuidString = ConfigSerializationUtil.getString(map, key, nullable);
+        if (uuidString == null) return null;
+        return UUID.fromString(uuidString);
+    }
+
+    public static <T> T getObject(Class<T> clazz, Map<?, ?> map, String key, boolean nullable) {
+        final Object object = map.get(key);
+        if (clazz.isInstance(object)) {
+            return clazz.cast(object);
+        }
+        if (object == null) {
+            if (!nullable) {
+                throw new NoSuchElementException(map + " does not contain " + key);
+            }
+            return null;
+        }
+        throw new IllegalArgumentException(key + "(" + object + ") is not a valid " + clazz);
+    }
+
+    private ConfigSerializationUtil() {
+    }
+}