Configuration problem: spring-security-web classes are not available. You need ...

Hello.
I'm working with STS 2.6.1 and Spring security 3.1.0 RC2

Here my spring security config:

Code:

---

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:flex="http://www.springframework.org/schema/flex"
        xmlns:security="http://www.springframework.org/schema/security"
        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
                http://www.springframework.org/schema/flex http://www.springframework.org/schema/flex/spring-flex-1.0.xsd
                http://www.springframework.org/schema/security http://www.springframework.org/schema/security/spring-security-3.1.xsd">

        <security:global-method-security
                secured-annotations="enabled" jsr250-annotations="enabled" />
        <security:http entry-point-ref="preAuthenticatedEntryPoint">
                <security:anonymous enabled="false" />
        </security:http>
        <bean id="preAuthenticatedEntryPoint"
                class="org.springframework.security.web.authentication.Http403ForbiddenEntryPoint" />

        <security:authentication-manager>
                <security:authentication-provider>
                        <security:user-service>
                                <security:user name="dd" authorities="ROLE_USER" />
                        </security:user-service>
                </security:authentication-provider>
        </security:authentication-manager>

</beans>

---

In the line <security:http> above, STS writes the error "Configuration problem: spring-security-web classes are not available. You need these to use <http>".

I'm sure all the spring security jar libraries are available (all the other XML security tags work fine) and located in WEB-INF/lib directory. Refresh project, clean project already done. Could you please help me?
Thank you

Pbesi

Either the spring-security-web jar, or one of its required dependencies are missing from the classpath. Check the FAQ and the dependency appendix in the manual for more information on what dependencies are needed and how to make sure you have them.

I get the same error at design time in the context xml file.

I think this is because of spring security 3.1, as another project where I used 3.0 did not have this issue.
I am using STS 2.8.0

Initially I thought I had an issue with spring security 3.1, but actually it was because I was importing too many dependencies using maven.

Importing just a few required spring jars, cleaning and rebuilding the project solved the issue, and I no longer get the error in my application context xml file