E2-1537: add method to clear content (#219)

* add method to clear user content locally

Author: e7mac

AndroidSDKCore/src/main/java/com/leanplum/Leanplum.java

@@ -2142,4 +2142,13 @@ private static void parseVariantDebugInfo(JSONObject response) {
       VarCache.setVariantDebugInfo(variantDebugInfo);
     }
   }
+
+  /**
+   * Clears cached values for messages, variables and test assignments.
+   * Use sparingly as if the app is updated, you'll have to deal with potentially
+   * inconsistent state or user experience.
+   */
+  public static void clearUserContent() {
+    VarCache.clearUserContent();
+  }
 }

AndroidSDKCore/src/main/java/com/leanplum/internal/VarCache.java

@@ -901,6 +901,22 @@ public static void saveUserAttributes() {
     SharedPreferencesUtil.commitChanges(editor);
   }
 
+  public static void clearUserContent() {
+    vars.clear();
+    variants.clear();
+    variantDebugInfo.clear();
+
+    diffs.clear();
+    messageDiffs.clear();
+    messages = null;
+    userAttributes = null;
+    merged = null;
+
+    devModeValuesFromServer = null;
+    devModeFileAttributesFromServer = null;
+    devModeActionDefinitionsFromServer = null;
+  }
+
   /**
    * Resets the VarCache to stock state.
    */