code: public Integer getCountAtOrAbove(final long version) {
          if (versionsStored < versionWindow.length) {
              return null;
          }
          int count = 0;
          for (int versionIdx = 0; versionIdx < versionWindow.length; versionIdx++) {
              if (versionWindow[versionIdx] >= version) {
                  count++;
              }
          }
  
          return count;
      }
docs: Get the count of blocks at or above the given version, within the window.
  
  @param version the block version to query.
  @return the count for the block version, or null if the window is not yet
  full.