add missing @since tag.

git-svn-id: https://google-guice.googlecode.com/svn/trunk@1448 d779f126-a31b-0410-b53b-1d3aecad763e
diff --git a/core/src/com/google/inject/util/Providers.java b/core/src/com/google/inject/util/Providers.java
index 5c7fa1e..ece6701 100644
--- a/core/src/com/google/inject/util/Providers.java
+++ b/core/src/com/google/inject/util/Providers.java
@@ -56,6 +56,8 @@
    * Returns a Guice-friendly {@code com.google.inject.Provider} for the given
    * JSR-330 {@code javax.inject.Provider}. The converse method is unnecessary,
    * since Guice providers directly implement the JSR-330 interface.
+   * 
+   * @since 3.0
    */
   public static <T> Provider<T> guicify(javax.inject.Provider<T> provider) {
     if (provider instanceof Provider) {