Fix NPE

bson/src/main/org/bson/internal/ChildCodecRegistry.java

@@ -63,7 +63,7 @@ public <U> Codec<U> get(final Class<U> clazz) {
         if (hasCycles(clazz)) {
             return new LazyCodec<U>(registry, clazz, types);
         } else {
-            return registry.get(new ChildCodecRegistry<>(this, clazz, null));
+            return registry.get(new ChildCodecRegistry<>(this, clazz, Collections.emptyList()));
         }
     }
 

bson/src/main/org/bson/internal/ProvidersCodecRegistry.java

@@ -65,7 +65,7 @@ public <T> Codec<T> get(final ChildCodecRegistry<T> context) {
             for (CodecProvider provider : codecProviders) {
                 Codec<T> codec = provider.get(context.getCodecClass(), context);
                 if (codec != null) {
-                    if (codec instanceof Parameterizable && context.getTypes() != null) {
+                    if (codec instanceof Parameterizable && !context.getTypes().isEmpty()) {
                         codec = (Codec<T>) ((Parameterizable) codec).parameterize(context, context.getTypes());
                     }
                     return codecCache.putIfMissing(codecCacheKey, codec);