Apache Pig project (http://pig.apache.org/) has the following constant in one of source files:
private static final char SINGLE_QUOTE = '\u005c'';

(Here backslash character in the literal quoted with unicode escape \u005c.)
Clover 3.1.11 encounters problem rendering the syntax highlights in the html report for such file (trace below). The file is present in the report, and coverage inside it seems to be calculated correctly, but the file's source in the report is not colored completely.

2013-07-13 07:19:07.862 [clover-report] Failed to render syntax highlights for /home/jenkins/jenkins/workspace/Pig-Integration-trunk-gd/pig/src/org/apache/pig/parser/StreamingCommandUtils.java: expecting ''', found '\n'
2013-07-13 07:19:07.863 [clover-report] line 47:56: expecting ''', found '\n'line 47:56: expecting ''', found '\n'
2013-07-13 07:19:07.863 [clover-report] at com.atlassian.clover.instr.java.JavaLexer.nextToken(JavaLexer.java:441)
2013-07-13 07:19:07.864 [clover-report] at com.atlassian.clover.instr.java.UnicodeJavaLexer.nextToken(UnicodeJavaLexer.java:56)
2013-07-13 07:19:07.864 [clover-report] at com.cenqua.clover.reporters.html.source.java.JavaTokenTraverser.traverse(JavaTokenTraverser.java:93)
2013-07-13 07:19:07.864 [clover-report] at com.cenqua.clover.reporters.html.source.java.JavaSourceRenderer.render(JavaSourceRenderer.java:18)
2013-07-13 07:19:07.865 [clover-report] at com.cenqua.clover.reporters.html.source.SourceRenderHelper.render(SourceRenderHelper.java:317)
2013-07-13 07:19:07.865 [clover-report] at com.cenqua.clover.reporters.html.source.SourceRenderHelper.gatherSrcRenderInfo(SourceRenderHelper.java:123)
2013-07-13 07:19:07.865 [clover-report] at com.cenqua.clover.reporters.html.source.SourceRenderHelper.insertLineInfosForFile(SourceRenderHelper.java:53)
2013-07-13 07:19:07.866 [clover-report] at com.cenqua.clover.reporters.html.RenderFileAction.insertLineInfos(RenderFileAction.java:284)
2013-07-13 07:19:07.866 [clover-report] at com.cenqua.clover.reporters.html.RenderFileAction.render(RenderFileAction.java:131)
2013-07-13 07:19:07.866 [clover-report] at com.cenqua.clover.reporters.html.RenderFileAction.call(RenderFileAction.java:115)
2013-07-13 07:19:07.867 [clover-report] at com.cenqua.clover.util.CloverExecutors$LoggingCallable.call(CloverExecutors.java:86)
2013-07-13 07:19:07.867 [clover-report] at clover.retrotranslator.edu.emory.mathcs.backport.java.util.concurrent.FutureTask.run(FutureTask.java:178)
2013-07-13 07:19:07.867 [clover-report] at clover.retrotranslator.edu.emory.mathcs.backport.java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1061)
2013-07-13 07:19:07.868 [clover-report] at clover.retrotranslator.edu.emory.mathcs.backport.java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:575)
2013-07-13 07:19:07.869 [clover-report] at java.lang.Thread.run(Thread.java:662)