Hi,
I'd like to contribute in order to improve the test quality and effectiveness of PDFBox. During mutation testing, I found that if the body of org.apache.pdfbox.pdmodel.graphics.state.RenderingMode.isFill()<https://github.com/apache/pdfbox/blob/trunk/pdfbox/src/main/java/org/apache/pdfbox/pdmodel/graphics/state/RenderingMode.java#L91> is replaced with return true; or return false;, no test case fails. To address this issue, I've opened a pull request on GitHub with a new test case for the method isFill()?. Please consider reviewing the pull request at https://github.com/apache/pdfbox/pull/88. Thanks, Deepika??
