Prevent NPE in CryptoIntegration.setProvider

Closes #38596

Signed-off-by: Leonid Rozenblyum <[email protected]>

Author: lrozenblyum

common/src/main/java/org/keycloak/common/crypto/CryptoIntegration.java

@@ -94,7 +94,7 @@ public static String dumpSecurityProperties() {
     }
 
     public static void setProvider(CryptoProvider provider) {
-        logger.debugf("Using the crypto provider: %s", provider.getClass().getName());
+        logger.debugf("Using the crypto provider: %s", provider != null ? provider.getClass().getName() : "null");
         cryptoProvider = provider;
     }
 }

common/src/test/java/org/keycloak/common/crypto/CryptoIntegrationTest.java

@@ -0,0 +1,36 @@
+package org.keycloak.common.crypto;
+
+import static org.junit.Assert.assertNull;
+
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+public class CryptoIntegrationTest {
+    private static CryptoProvider originalProvider;
+
+    @BeforeClass
+    public static void keepOriginalProvider() {
+        CryptoIntegrationTest.originalProvider = getSelectedProvider();
+    }
+
+    // doing our best to avoid any side effects on other tests by restoring the initial state of CryptoIntegration
+    @AfterClass
+    public static void restoreOriginalProvider() {
+        CryptoIntegration.setProvider(originalProvider);
+    }
+
+    @Test
+    public void canSetNullProvider() {
+        CryptoIntegration.setProvider(null);
+        assertNull(getSelectedProvider());
+    }
+
+    private static CryptoProvider getSelectedProvider() {
+        try {
+            return CryptoIntegration.getProvider();
+        } catch (IllegalStateException e) {
+            return null;
+        }
+    }
+}