IntelliJ highlight "out.println" in JSP as red error

Some times you might have a Maven web application that deployes without problem into a Tomcat server, but when open in IntelliJ IDE, you will notice some of your JSP files have red error marks on lines such as out.println("test");. This problem can occur if your project pom.xml did not include jsp-api as provided dependency to your project! So ensure it contains these in your pom.xml file.

        <!-- Web -->
        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>javax.servlet.jsp-api</artifactId>
            <version>2.3.1</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
            <version>1.2</version>
        </dependency>

Note that for Tomcat, you must include the JSTL tag library as dependency, and it is NOT provided by server if you want to use the core JSTL tags!