Jasig/sass-maven-plugin — pull request #2 by rasmushaglund (2012-06-11 10:57:50+00:00)
Title: Fixed maven dependency problem for com/google/common/collect/ImmutableMap

When running a target I get:

Internal error in the plugin manager executing goal 'org.jasig.maven:sass-maven-plugin:1.0.1-SNAPSHOT:watch': Unable to load the mojo 'org.jasig.maven:sass-maven-plugin:1.0.1-SNAPSHOT:watch' in the plugin 'org.jasig.maven:sass-maven-plugin'. A required class is missing: com/google/common/collect/ImmutableMap
com.google.common.collect.ImmutableMap

Adding a maven dependency for com.google.common.collect solved the problem