code: public void append(int key, boolean value) {
          if (mSize != 0 && key <= mKeys[mSize - 1]) {
              put(key, value);
              return;
          }
          mKeys = GrowingArrayUtils.append(mKeys, mSize, key);
          mValues = GrowingArrayUtils.append(mValues, mSize, value);
          mSize++;
      }
docs: Puts a key/value pair into the array, optimizing for the case where
  the key is greater than all existing keys in the array.