There are two things.
One is that China's human rights infrastructure really grew out of its initial condemnation in the UN subcommittee on human rights in 1989. But once the infrastructure was built up--it was built up by the state to defend China against attacks--that then becomes a conduit for human rights norms and practices, and for human rights documents to be translated into Chinese usage.
Another example on this same score is that legislative hearings, public hearings, became part of China's practice after China joined the WTO. It was part of its WTO commitments to have public hearings on trade-related matters, but it then becomes a generalized matter in the legislative arena. That just shows you how international practice does influence China.