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org.w3c.css.properties.css21.Css21Style cannot be cast to org.w3c.css.properties.css3.Css3Style Unknown error java.lang.RuntimeException: org.w3c.css.properties.css21.Css21Style cannot be cast to org.w3c.css.properties.css3.Css3Style
Do you have more info in the trace? This is not enough to track where this happens, unfortunately.