Expose widely used Base(Map)Test util methods as public static (#4133)

Author: JooHyukKim

src/test/java/com/fasterxml/jackson/databind/BaseMapTest.java

@@ -238,13 +238,15 @@ protected ObjectReader objectReader(Class<?> cls) {
         return sharedMapper().readerFor(cls);
     }
 
+    // `public` since 2.16, was only `protected` before then.
     // @since 2.10
-    protected static ObjectMapper newJsonMapper() {
+    public static ObjectMapper newJsonMapper() {
         return new JsonMapper();
     }
 
+    // `public` since 2.16, was only `protected` before then.
     // @since 2.10
-    protected static JsonMapper.Builder jsonMapperBuilder() {
+    public static JsonMapper.Builder jsonMapperBuilder() {
         return JsonMapper.builder();
     }
 

src/test/java/com/fasterxml/jackson/databind/BaseTest.java

@@ -437,7 +437,8 @@ protected byte[] encodeInUTF32BE(String input)
         return result;
     }
 
-    public String q(String str) {
+    // `static` since 2.16, was only `public` before then.
+    public static String q(String str) {
         return '"'+str+'"';
     }
 
@@ -446,7 +447,8 @@ public String quote(String str) {
         return q(str);
     }
 
-    protected static String a2q(String json) {
+    // `public` since 2.16, was only `protected` before then.
+    public static String a2q(String json) {
         return json.replace("'", "\"");
     }