diff --git a/src/main/core-api/java/com/mysql/cj/util/Util.java b/src/main/core-api/java/com/mysql/cj/util/Util.java
index acdd86085..e7a91082a 100644
--- a/src/main/core-api/java/com/mysql/cj/util/Util.java
+++ b/src/main/core-api/java/com/mysql/cj/util/Util.java
@@ -307,8 +307,9 @@ public static <T> List<T> loadClasses(String extensionClassNames, String errorMe
      * @return boolean
      */
     public static boolean isJdbcInterface(Class<?> clazz) {
-        if (Util.isJdbcInterfaceCache.containsKey(clazz)) {
-            return (Util.isJdbcInterfaceCache.get(clazz));
+        final Boolean isJdbcInterface = Util.isJdbcInterfaceCache.get(clazz);
+        if (isJdbcInterface != null) {
+            return isJdbcInterface;
         }
 
         if (clazz.isInterface()) {
diff --git a/src/main/user-impl/java/com/mysql/cj/jdbc/ha/plugins/failover/FailoverConnectionPlugin.java b/src/main/user-impl/java/com/mysql/cj/jdbc/ha/plugins/failover/FailoverConnectionPlugin.java
index ff06a8b70..5f58b98f7 100644
--- a/src/main/user-impl/java/com/mysql/cj/jdbc/ha/plugins/failover/FailoverConnectionPlugin.java
+++ b/src/main/user-impl/java/com/mysql/cj/jdbc/ha/plugins/failover/FailoverConnectionPlugin.java
@@ -67,10 +67,14 @@
 import java.util.Map;
 import java.util.Objects;
 import java.util.Properties;
+import java.util.Set;
 import java.util.concurrent.Callable;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.function.Supplier;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 /**
  * A {@link IConnectionPlugin} implementation that provides cluster-aware failover
@@ -92,22 +96,26 @@ public class FailoverConnectionPlugin implements IConnectionPlugin {
   static final String METHOD_CLOSE = "close";
   static final String METHOD_IS_CLOSED = "isClosed";
 
-  private static final List<String> METHODS_REQUIRE_UPDATED_TOPOLOGY = new ArrayList<>(Arrays.asList(
-      METHOD_COMMIT,
-      "connect",
-      "isValid",
-      "rollback",
-      "setAutoCommit",
-      "setReadOnly",
-      "execute",
-      "executeBatch",
-      "executeLargeBatch",
-      "executeLargeUpdate",
-      "executeQuery",
-      "executeUpdate",
-      "executeWithFlags",
-      "getParameterMetaData"
-  ));
+  private final static Set<String> METHODS_REQUIRE_UPDATED_TOPOLOGY = ConcurrentHashMap.newKeySet();
+
+  static {
+    METHODS_REQUIRE_UPDATED_TOPOLOGY.addAll(Arrays.asList(
+        METHOD_COMMIT,
+        "connect",
+        "isValid",
+        "rollback",
+        "setAutoCommit",
+        "setReadOnly",
+        "execute",
+        "executeBatch",
+        "executeLargeBatch",
+        "executeLargeUpdate",
+        "executeQuery",
+        "executeUpdate",
+        "executeWithFlags",
+        "getParameterMetaData"
+    ));
+  }
 
   private static final String METHOD_GET_TRANSACTION_ISOLATION =
       "getTransactionIsolation";