Use the latest fbjni

libs/fbjni/java/com/facebook/jni/MapIteratorHelper.java

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+/**
+ * Copyright 2018-present, Facebook, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.facebook.jni;
+
+import com.facebook.jni.annotations.DoNotStrip;
+import java.util.Iterator;
+import java.util.Map;
+import javax.annotation.Nullable;
+
+/**
+ * To iterate over a Map from C++ requires four calls per entry: hasNext(), next(), getKey(),
+ * getValue(). This helper reduces it to one call and two field gets per entry. It does not use a
+ * generic argument, since in C++, the types will be erased, anyway. This is *not* a {@link
+ * java.util.Iterator}.
+ */
+@DoNotStrip
+public class MapIteratorHelper {
+  @DoNotStrip private final Iterator<Map.Entry> mIterator;
+  @DoNotStrip private @Nullable Object mKey;
+  @DoNotStrip private @Nullable Object mValue;
+
+  @DoNotStrip
+  public MapIteratorHelper(Map map) {
+    mIterator = map.entrySet().iterator();
+  }
+
+  /**
+   * Moves the helper to the next entry in the map, if any. Returns true iff there is an entry to
+   * read.
+   */
+  @DoNotStrip
+  boolean hasNext() {
+    if (mIterator.hasNext()) {
+      Map.Entry entry = mIterator.next();
+      mKey = entry.getKey();
+      mValue = entry.getValue();
+      return true;
+    } else {
+      mKey = null;
+      mValue = null;
+      return false;
+    }
+  }
+}