JSP optimize-scriplets causes compilation failure when string concatenation exists inside method arguments in expression on EAP 6.x/7.x

Environment

• Red Hat JBoss Enterprise Application Platform (EAP)
  • 6.x
  • 7.x

Issue

In EAP 7, when optimize-scriplets="true" is enabled in undertow subsystem and a JSP has the following expression which string concatenation exists inside method arguments:

<img src='<%=response.encodeURL(request.getContextPath() + "/image/test.jpg")%>'/>

The JSP request fails due to compile error with the following log message:

ERROR [io.undertow.request] (default task-1) UT005023: Exception handling request to /test/example.jsp: org.apache.jasper.JasperException: JBWEB004062: Unable to compile class for JSP: 
 
JBWEB004060: An error occurred at line: 1 in the jsp file: /example.jsp
The method print(String) in the type JspWriter is not applicable for the arguments (String, void)
1: <img src='<%=response.encodeURL(request.getContextPath() + "/image/test.jpg")%>'/>
 
 
JBWEB004060: An error occurred at line: 1 in the jsp file: /example.jsp
Syntax error on token ";", , expected
1: <img src='<%=response.encodeURL(request.getContextPath() + "/image/test.jpg")%>'/>
 
 
Stacktrace:
	at org.apache.jasper.compiler.DefaultErrorHandler.javacError(DefaultErrorHandler.java:95)
	at org.apache.jasper.compiler.ErrorDispatcher.javacError(ErrorDispatcher.java:198)
	at org.apache.jasper.compiler.JDTCompiler.generateClass(JDTCompiler.java:455)
	at org.apache.jasper.compiler.Compiler.compile(Compiler.java:359)
	at org.apache.jasper.compiler.Compiler.compile(Compiler.java:334)
	at org.apache.jasper.compiler.Compiler.compile(Compiler.java:321)
	at org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:652)
	at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:358)
	at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:403)
	at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:347)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
	...

The same issue also happens on EAP 6 when -Dorg.apache.jasper.compiler.Parser.OPTIMIZE_SCRIPTLETS=true is enabled.

Resolution

• This issue is reported as the following JIRAs, which will be fixed in the future releases (EAP 7.1.6 and 7.2.1 tentatively):
  • EAP 7.1.z: Content from issues.jboss.org is not included.JBEAP-15597
  • EAP 7.2.z: Content from issues.jboss.org is not included.JBEAP-15746
• Until the above JIRA is fixed, avoid using the option optimize-scriplets="true" in EAP 7 and the system property -Dorg.apache.jasper.compiler.Parser.OPTIMIZE_SCRIPTLETS=true in EAP 6 when you have such expression in JSP.

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