handle null issuer value

Author: richard-dennehy

x-pack/plugin/security/src/main/java/org/elasticsearch/xpack/security/authc/saml/SamlObjectHandler.java

@@ -269,7 +269,7 @@ private ElasticsearchSecurityException samlSignatureException(Issuer issuer, Lis
 
     // package private for testing
     String describeIssuer(@Nullable Issuer issuer) {
-        if (issuer == null) {
+        if (issuer == null || issuer.getValue() == null) {
             return "";
         }
         final String msg = " The issuer included in the SAML message was [%s]";

x-pack/plugin/security/src/test/java/org/elasticsearch/xpack/security/authc/saml/SamlAuthenticatorTests.java

@@ -1377,6 +1377,11 @@ public void testDescribeNullIssuer() {
         assertThat(authenticator.describeIssuer(null), equalTo(""));
     }
 
+    public void testDescribeNullIssuerValue() {
+        final Issuer issuer = new IssuerBuilder().buildObject();
+        assertThat(authenticator.describeIssuer(issuer), equalTo(""));
+    }
+
     public void testDescribeIssuer() {
         final Issuer issuer = new IssuerBuilder().buildObject();
         issuer.setValue("https://idp.saml.elastic.test/");