Use message in all Assert

This ensures compatibility with Spring 5.

Fixes gh-4193

web/src/main/java/org/springframework/security/web/authentication/AnonymousAuthenticationFilter.java

@@ -84,7 +84,7 @@ public class AnonymousAuthenticationFilter extends GenericFilterBean implements
 
 	@Override
 	public void afterPropertiesSet() {
-		Assert.hasLength(key);
+		Assert.hasLength(key, "key must have length");
 		Assert.notNull(principal, "Anonymous authentication principal must be set");
 		Assert.notNull(authorities, "Anonymous authorities must be set");
 	}

web/src/main/java/org/springframework/security/web/authentication/preauth/PreAuthenticatedGrantedAuthoritiesUserDetailsService.java

@@ -54,7 +54,7 @@ public class PreAuthenticatedGrantedAuthoritiesUserDetailsService implements
 	 */
 	public final UserDetails loadUserDetails(PreAuthenticatedAuthenticationToken token)
 			throws AuthenticationException {
-		Assert.notNull(token.getDetails());
+		Assert.notNull(token.getDetails(), "token.getDetails() cannot be null");
 		Assert.isInstanceOf(GrantedAuthoritiesContainer.class, token.getDetails());
 		Collection<? extends GrantedAuthority> authorities = ((GrantedAuthoritiesContainer) token
 				.getDetails()).getGrantedAuthorities();

web/src/main/java/org/springframework/security/web/authentication/session/SessionFixationProtectionEvent.java

@@ -48,8 +48,8 @@ public class SessionFixationProtectionEvent extends AbstractAuthenticationEvent
 	public SessionFixationProtectionEvent(Authentication authentication,
 			String oldSessionId, String newSessionId) {
 		super(authentication);
-		Assert.hasLength(oldSessionId);
-		Assert.hasLength(newSessionId);
+		Assert.hasLength(oldSessionId, "oldSessionId must have length");
+		Assert.hasLength(newSessionId, "newSessionId must have length");
 		this.oldSessionId = oldSessionId;
 		this.newSessionId = newSessionId;
 	}

web/src/main/java/org/springframework/security/web/util/RedirectUrlBuilder.java

@@ -68,8 +68,8 @@ public class RedirectUrlBuilder {
 	public String getUrl() {
 		StringBuilder sb = new StringBuilder();
 
-		Assert.notNull(scheme);
-		Assert.notNull(serverName);
+		Assert.notNull(scheme, "scheme cannot be null");
+		Assert.notNull(serverName, "serverName cannot be null");
 
 		sb.append(scheme).append("://").append(serverName);