Add comments to ClassLoader scoped weak map

dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/ClassLoaderScopedWeakMap.java

@@ -4,12 +4,17 @@ import datadog.trace.bootstrap.WeakMap;
 import java.util.HashMap;
 import java.util.Map;
 
+/** A registry which is scoped per-classloader able to hold key-value pairs with weak keys. */
 public class ClassLoaderScopedWeakMap {
 
   public static final ClassLoaderScopedWeakMap INSTANCE = new ClassLoaderScopedWeakMap();
 
   private final WeakMap<ClassLoader, Map<Object, Object>> map = WeakMap.Supplier.DEFAULT.get();
 
+  /**
+   * Gets the element registered at the specified key or register as new one retrieved by the
+   * provided supplier.
+   */
   public synchronized Object getOrCreate(
       ClassLoader classLoader, Object key, Supplier valueSupplier) {
     Map<Object, Object> classLoaderMap = map.get(classLoader);
@@ -27,6 +32,10 @@ public class ClassLoaderScopedWeakMap {
     return value;
   }
 
+  /**
+   * Supplies the value to be stored and it is called only when a value does not exists yet in the
+   * registry.
+   */
   public interface Supplier {
     Object get();
   }