hadoop-compat/src/main/java/com/twitter/elephantbird/util/HadoopCompat.java
public static long getDefaultBlockSize(FileSystem fs, Path path) {
    return (Long)
        (HadoopCompat.isVersion2x()
            ? invoke(GET_DEFAULT_BLOCK_SIZE_METHOD, fs, path)
            : invoke(GET_DEFAULT_BLOCK_SIZE_METHOD, fs));
  }
public static long getDefaultBlockSize(FileSystem fs, Path path) {
    return (Long)
        (HadoopCompat.isVersion2x()
            ? invoke(GET_DEFAULT_BLOCK_SIZE_METHOD, fs, path)
            : invoke(GET_DEFAULT_BLOCK_SIZE_METHOD, fs));
  }
This method invokes getDefaultBlocksize() without path on Hadoop 1 and
with Path on Hadoop 2.

Older versions of Hadoop 1 do not have
{@link FileSystem#getDefaultBlocksize(Path)}. This api exists in Hadoop 2
and recent versions of Hadoop 1. Path argument is required for viewfs filesystem
in Hadoop 2. <p>