title: java.lang.NoClassDefFoundError: org/apache/taglibs/standard/tag/rt/core/ImportTag
body: <p>I'm trying to understand the taglibs from jstl, so i decided to download the sources for it.
  My test app was working with the following jars:</p>
  
  <p>javax.servlet.jsp.jstl-1.2.1.jar
  javax.servlet.jsp.jstl-api-1.2.1.jar</p>
  
  <p>Then i changed for:</p>
  
  <p>javax.servlet.jsp.jstl-1.2.1-sources.jar
  javax.servlet.jsp.jstl-api-1.2.1-sources.jar</p>
  
  <p>and then i got the error on the title. I don't know why it's not founding the ImportTag. Using archive manager to open the .jar, i can see the ImportTag.java. But when i put the jar on the WEB-INF/lib, and checks the jar through eclipse, all i see is this:</p>
  
  <p>Here's my web.xml</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0"&gt;
    &lt;display-name&gt;agenda&lt;/display-name&gt;
  
    &lt;error-page&gt;
      &lt;exception-type&gt;java.lang.Exception&lt;/exception-type&gt;
      &lt;location&gt;/erro.html&lt;/location&gt;
    &lt;/error-page&gt;
  
    &lt;error-page&gt;
      &lt;error-code&gt;404&lt;/error-code&gt;
      &lt;location&gt;/404.html&lt;/location&gt;
    &lt;/error-page&gt;
  &lt;/web-app&gt;
  </code></pre>
  
  <p>I'm using tomcat 7 and Java 7.</p>
  
  <p>Any ideas??</p>
  
  <p>Thanks in advance.</p>