A specialized implementation of the {@code Lookup} interface that allowsaccess to system properties.
This implementation relies on {@code StrLookup.systemPropertiesLookup()} fromthe Commons Lang project to resolve system properties. It can be used for referencing system properties in configuration files in an easy way, for instance:
current.user = ${sys:user.name}
{@code SystemPropertiesLookup} is one of the standard lookups that isregistered per default for each configuration.
@version $Id: SystemPropertiesLookup.java 1624601 2014-09-12 18:04:36Z oheger $
@since 2.0