downgrade Google Guava from 26.0 to 24.1 to fix issues with SpotBugs.
<!-- Google Core Libraries for Java
Contains a lot of helpful data structures. -->
- <dependency org="com.google.guava" name="guava" rev="26.0-jre" conf="core->default; contrib->sources"/>
+ <dependency org="com.google.guava" name="guava" rev="24.1-jre" conf="core->default; contrib->sources"/>
<!-- Guava-testlib contains many useful testing utilities -->
- <dependency org="com.google.guava" name="guava-testlib" rev="26.0-jre" conf="test->default; contrib->sources"/>
+ <dependency org="com.google.guava" name="guava-testlib" rev="24.1-jre" conf="test->default; contrib->sources"/>
<!-- Dependency on Ivy itself so that we can ugprade it easily.
Change version number in build.xml for upgrading. -->
