Contains the "phase 2" client certificate if used by the EAP method specified in the phase2_auth or phase2_autheap properties.
Certificate data is specified using a "scheme"; two are currently supported: blob and path. When using the blob scheme (which is backwards compatible with NM 0.7.x) this property should be set to the certificate's DER encoded data. When using the path scheme, this property should be set to the full UTF-8 encoded path of the certificate, prefixed with the string "file://" and ending with a terminating NUL byte. This property can be unset even if the EAP method supports CA certificates, but this allows man-in-the-middle attacks and is NOT recommended.
Setting this property directly is discouraged; use the set_phase2_client_cert function instead.