Fix slf4j double inclusion
<artifactId>wdtk-datamodel</artifactId>
<version>0.9.0</version>
</dependency>
+ <dependency>
+ <groupId>org.slf4j</groupId>
+ <artifactId>slf4j-api</artifactId>
+ <version>1.7.18</version>
+ <scope>provided</scope>
+ </dependency>
<!-- testing dependencies -->
