Avoid blocking non-reproducible randomness in test (#36561)

The security documentation test uses
SecureRandom#getStrongInstance. This defaults to
securerandom.strongAlgorithms=NativePRNGBlocking:SUN,DRBG:SUN which
means a blocking implementation that reads from /dev/random. This means
that this test can stall if the entropy on the machine is
exhausted. Anyway, it also means that the randomness is
non-reproducible, a thing that we try to avoid in tests. This commit
switches to a boring randomness source to avoid the blocking, and to
keep the test reproducible.

Author: jasontedor

client/rest-high-level/src/test/java/org/elasticsearch/client/documentation/SecurityDocumentationIT.java

@@ -71,19 +71,21 @@
 import org.elasticsearch.client.security.support.expressiondsl.expressions.AnyRoleMapperExpression;
 import org.elasticsearch.client.security.support.expressiondsl.fields.FieldRoleMapperExpression;
 import org.elasticsearch.client.security.user.User;
-import org.elasticsearch.client.security.user.privileges.Role;
 import org.elasticsearch.client.security.user.privileges.ApplicationPrivilege;
+import org.elasticsearch.client.security.user.privileges.ApplicationResourcePrivileges;
 import org.elasticsearch.client.security.user.privileges.IndicesPrivileges;
+import org.elasticsearch.client.security.user.privileges.Role;
+import org.elasticsearch.client.security.user.privileges.UserIndicesPrivileges;
 import org.elasticsearch.common.util.set.Sets;
 import org.hamcrest.Matchers;
 
 import javax.crypto.SecretKeyFactory;
 import javax.crypto.spec.PBEKeySpec;
+
 import java.io.IOException;
-import java.security.SecureRandom;
-import java.util.Base64;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Base64;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.Iterator;
@@ -94,8 +96,8 @@
 import java.util.concurrent.TimeUnit;
 
 import static org.hamcrest.Matchers.contains;
-import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.containsInAnyOrder;
+import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.empty;
 import static org.hamcrest.Matchers.emptyIterable;
 import static org.hamcrest.Matchers.equalTo;
@@ -128,7 +130,8 @@ public void testPutUser() throws Exception {
         }
         {
             byte[] salt = new byte[32];
-            SecureRandom.getInstanceStrong().nextBytes(salt);
+            // no need for secure random in a test; it could block and would not be reproducible anyway
+            random().nextBytes(salt);
             char[] password = new char[]{'p', 'a', 's', 's', 'w', 'o', 'r', 'd'};
             User user = new User("example2", Collections.singletonList("superuser"));