why this method return null?

[zsbox]

why this method return null, is useless? and HardLineBreakSyntax, SoftLineBreakSyntax

None of these methods seem to work！how to use it?

[chenzhiguang]

It is used to move the reading position forward and skip blank lines, the same to SoftLineBreakSyntax. HardLineBreakSyntax has its job to do.

Please refer to these references regarding blank lines, soft line breaks, and hard line breaks.
https://spec.commonmark.org/0.30/#blank-lines
https://spec.commonmark.org/0.30/#hard-line-breaks
https://spec.commonmark.org/0.30/#soft-line-breaks