just fall back to simple class name

spring-auto-restdocs-core/src/main/java/capital/scalable/restdocs/constraints/HumanReadableConstraintResolver.java

@@ -88,9 +88,7 @@ private String humanReadableString(Object o) {
             try {
                 return ((Class) o).newInstance().toString();
             } catch (InstantiationException | IllegalAccessException e) {
-                log.error("Failed to create an instance of {}", ((Class) o).getCanonicalName(), e);
-                return "Failed to create an instance of " + ((Class) o).getCanonicalName() +
-                        ". Does the class have a no args constructor?";
+                return ((Class) o).getSimpleName();
             }
         } else {
             return o.toString();

spring-auto-restdocs-core/src/test/java/capital/scalable/restdocs/constraints/HumanReadableConstraintResolverTest.java

@@ -58,6 +58,7 @@ public void testHumanReadable() {
         configuration.put("class", CustomConstraint.class);
         configuration.put("groups", new Class<?>[]{Update.class});
         configuration.put("payload", new Class<?>[0]);
+        configuration.put("ref", Entity.class);
         Constraint constraint = new Constraint("Custom", configuration);
 
         when(delegate.resolveForProperty("prop", this.getClass()))
@@ -68,13 +69,13 @@ public void testHumanReadable() {
         List<Constraint> constraints = resolver.resolveForProperty("prop", this.getClass());
         assertConstraints(constraints);
 
-        constraints = resolver.resolveForParameter(Mockito.mock(MethodParameter.class));
+        constraints = resolver.resolveForParameter(mock(MethodParameter.class));
         assertConstraints(constraints);
     }
 
     private void assertConstraints(List<Constraint> constraints) {
         assertThat(constraints.size(), is(1));
-        assertThat(constraints.get(0).getConfiguration().size(), is(7));
+        assertThat(constraints.get(0).getConfiguration().size(), is(8));
         assertThat(constraints.get(0).getConfiguration().get("primitive").toString(), is("1"));
         assertThat(constraints.get(0).getConfiguration().get("wrapper").toString(), is("1"));
         assertThat(constraints.get(0).getConfiguration().get("object").toString(), is("I'm Peter"));
@@ -85,6 +86,7 @@ private void assertConstraints(List<Constraint> constraints) {
         // groups and payload belong to the fields that is not touched
         assertThat(constraints.get(0).getConfiguration().get("groups"), instanceOf(Class[].class));
         assertThat(constraints.get(0).getConfiguration().get("payload"), instanceOf(Class[].class));
+        assertThat(constraints.get(0).getConfiguration().get("ref").toString(), is("Entity"));
     }
 
     static class CustomObj {
@@ -106,4 +108,9 @@ public String toString() {
             return "I'm custom constraint";
         }
     }
+
+    static class Entity {
+        Entity(String name) {
+        }
+    }
 }