In order for your server to support Expand and HSPC integration it is necessary to install the following RPMs
from the 'opt/api' directory in your Plesk archive
psa-api-rpc-7.5.3-suse9.1.build75050523.15.noarch.rpm
psa-api-rpc-doc-7.5.3-suse9.1.build75050523.15.noarch.rpm
psa-api-rpc-protocol-7.5.3-suse9.1.build75050523.15.noarch.rpm
However these packages are not required for Plesk to function properly.