@Override
	public String convert(ILoggingEvent iLoggingEvent) {
		return version;
	}
Implementation of {@link ch.qos.logback.classic.pattern.ClassicConverter}
that returns the "Implementation-Version" string obtained from the
manifest of the jar that this class was loaded from.
<p>
If this class was <b>not</b> loaded from a jar file or if
the manifest cannot be loaded, a default version string
of {@code unknown} is returned.

@author Patrick Peralta
@author David Turanski
spring-xd-dirt/src/main/java/org/springframework/xd/dirt/util/logging/VersionPatternConverter.java