Merging minor piece of #4101

Author: cowtowncoder

src/main/java/com/fasterxml/jackson/databind/ObjectMapper.java

@@ -2272,9 +2272,14 @@ public ObjectMapper setConstructorDetector(ConstructorDetector cd) {
     /**
      * Method for specifying {@link CacheProvider} instance, to provide Cache instances to be used in components downstream.
      *
+     * @cacheProvider Cache provider for this mapper to use
+     *
+     * @throws IllegalArgumentException if given provider is null
+     *
      * @since 2.16
      */
     public ObjectMapper setCacheProvider(CacheProvider cacheProvider) {
+        _assertNotNull("cacheProvider", cacheProvider);
         _deserializationConfig = _deserializationConfig.with(cacheProvider);
         _serializationConfig = _serializationConfig.with(cacheProvider);
         return this;

src/main/java/com/fasterxml/jackson/databind/deser/DeserializerCache.java

@@ -24,6 +24,13 @@ public final class DeserializerCache
 {
     private static final long serialVersionUID = 1L;
 
+    /**
+     * Default size of the underlying cache to use.
+     * 
+     * @since 2.16
+     */
+    public final static int DEFAULT_MAX_CACHE_SIZE = 2000;
+
     /*
     /**********************************************************
     /* Caching
@@ -52,7 +59,7 @@ public final class DeserializerCache
      */
 
     public DeserializerCache() {
-        this(2000); // see [databind#1995]
+        this(DEFAULT_MAX_CACHE_SIZE); // see [databind#1995]
     }
 
     public DeserializerCache(int maxSize) {