Encapsulate the object field in Pooled (#213)

src/main/java/stormpot/Pooled.java

@@ -23,7 +23,10 @@
 public class Pooled<T> extends BasePoolable implements Poolable, AutoCloseable {
   /**
    * The object managed by this pooled instance.
+   *
+   * @deprecated Use {@link #getObject()} instead.
    */
+  @Deprecated
   public final T object;
 
   /**
@@ -37,6 +40,14 @@ public Pooled(Slot slot, T object) {
     this.object = object;
   }
 
+  /**
+   * Get the pooled object.
+   * @return The pooled object held by this {@link Pooled} reference.
+   */
+  public T getObject() {
+    return object;
+  }
+
   /**
    * {@link Pooled} implements {@link AutoCloseable} as a convenient way to release
    * claimed objects back to the pool, using the try-with-resources syntax.