code: public boolean isConsistent() throws IOException {
          byte[] b = new byte[elementSize];
          long offset = 0;
          byte[] oldKey = null;
          int i = 0;
          while (offset < this.getFilledUpFromContentStart()) {
              this.read(offset, ByteBuffer.wrap(b));
              byte[] key = Arrays.copyOfRange(b, 0, keySize);
              if (oldKey != null && KeyUtils.compareKey(key, oldKey) != 1) {
                  logger.error("File is not consistent at record {}. {} not larger than {}", new Object[] { i,
                          KeyUtils.toStringUnsignedInt(key), KeyUtils.toStringUnsignedInt(oldKey) });
                  return false;
              }
              oldKey = Arrays.copyOf(key, keySize);
              offset += elementSize;
              i++;
          }
          return true;
      }
docs: This method checks, if the keys of all inserted elements are incrementing continuously.
  
  @return true, if the file fulfills this constraint.
  @throws IOException