This artifact originates from the Orbit Project at Eclipse, it is an osgi bundle and is signed as well.
'org.eclipse.jetty.orbit:javax.transaction:1.1.1.v201105210645'
<dependency>
<groupId>org.eclipse.jetty.orbit</groupId>
<artifactId>javax.transaction</artifactId>
<version>1.1.1.v201105210645</version>
</dependency>
<dependency org="org.eclipse.jetty.orbit" name="javax.transaction" rev="1.1.1.v201105210645"/>
"org.eclipse.jetty.orbit", "javax.transaction", "1.1.1.v201105210645"