src/main/java/com/googlecode/javaewah/datastructure/ImmutableBitSet.java
public IntIterator unsetIntIterator() {
      return new IntIterator() {
          @Override
          public boolean hasNext() {
              return this.i >= 0;
          }

          @Override
          public int next() {
              this.j = this.i;
              this.i = ImmutableBitSet.this.nextUnsetBit(this.i + 1);
              return this.j;
          }

          private int i = ImmutableBitSet.this.nextUnsetBit(0);

          private int j;
      };
  }
public IntIterator unsetIntIterator() {
      return new IntIterator() {
          @Override
          public boolean hasNext() {
              return this.i >= 0;
          }

          @Override
          public int next() {
              this.j = this.i;
              this.i = ImmutableBitSet.this.nextUnsetBit(this.i + 1);
              return this.j;
          }

          private int i = ImmutableBitSet.this.nextUnsetBit(0);

          private int j;
      };
  }
Iterate over the unset bits

@return an iterator