Make these methods simple wrappers around SSL_CTX_set_{min,max}_proto_version(). When we introduced these methods in commit https://github.com/ruby/openssl/commit/18603949d316 [1], which went to v2.1.0, we added a private method to SSLContext that set both the minimum and maximum protocol versions at the same time. This was to allow emulating the behavior using SSL options on older OpenSSL versions that lack SSL_CTX_set_{min,max}_proto_version(). Since we no longer support OpenSSL 1.0.2, the related code has already been removed. In OpenSSL 1.1.1 or later, setting the minimum or maximum version to 0 is not equivalent to leaving it unset. Similar to SSL options, which we avoid overwriting as of commit https://github.com/ruby/openssl/commit/00bec0d905d5 and commit https://github.com/ruby/openssl/commit/77c3db2d6587 [2], a system-wide configuration file may define a default protocol version bounds. Setting the minimum version should not unset the maximum version, and vice versa. [1] https://github.com/ruby/openssl/pull/142 [2] https://github.com/ruby/openssl/pull/767 https://github.com/ruby/openssl/commit/5766386321