Enhancement: support generating UUID in XSLT

[jindrichmynarz]

In many cases, there are no natural identifiers in the data transformed by LP-ETL. In such cases blank nodes or UUID-based IRIs can be used. Since the use of blank nodes is generally discouraged, it would be useful if the XSLT component allowed to generate UUIDs. This can be worked around by generating blank nodes, followed by a SPARQL Update operation to rewrite them to UUID-based IRIs, but that is not as convenient.

This is the issue as in UnifiedViews/Plugins#128.

[jakubklimek]

If the XSLT library does not support it, there is nothing we can do except for hacking it somehow.

[jindrichmynarz]

The Saxon XSLT processor offers extension functions for this. Does the XSLT component use Saxon?

[skodapetr]

From the t-xslt pom file:

        <dependency>
            <groupId>net.sf.saxon</groupId>
            <artifactId>Saxon-HE</artifactId>
            <version>9.6.0-7</version>
            <scope>compile</scope>
        </dependency>