docs: public boolean isValid() {
          if (ints == null) {
              throw new IllegalStateException("ints is null");
          }
          if (length < 0) {
              throw new IllegalStateException("length is negative: " + length);
          }
          if (length > ints.length) {
              throw new IllegalStateException("length is out of bounds: " + length + ",ints.length=" + ints.length);
          }
          if (offset < 0) {
              throw new IllegalStateException("offset is negative: " + offset);
          }
          if (offset > ints.length) {
              throw new IllegalStateException("offset out of bounds: " + offset + ",ints.length=" + ints.length);
          }
          if (offset + length < 0) {
              throw new IllegalStateException("offset+length is negative: offset=" + offset + ",length=" + length);
          }
          if (offset + length > ints.length) {
              throw new IllegalStateException("offset+length out of bounds: offset=" + offset + ",length=" + length + ",ints.length=" + ints.length);
          }
          return true;
      }