Revert "feat/conf_map_required (#4405)"

This reverts commit 12071d1.

Author: kevwan

core/mapping/unmarshaler.go

@@ -919,16 +919,12 @@ func (u *Unmarshaler) processNamedFieldWithoutValue(fieldType reflect.Type, valu
 	}
 
 	switch fieldKind {
-	case reflect.Array, reflect.Slice:
+	case reflect.Array, reflect.Map, reflect.Slice:
 		if !opts.optional() {
 			return u.processFieldNotFromString(fieldType, value, valueWithParent{
 				value: emptyMap,
 			}, opts, fullName)
 		}
-	case reflect.Map:
-		if !opts.optional() {
-			return newInitError(fullName)
-		}
 	case reflect.Struct:
 		if !opts.optional() {
 			required, err := structValueRequired(u.key, derefedType)

core/mapping/unmarshaler_test.go

@@ -2432,42 +2432,6 @@ func TestUnmarshalMapOfStruct(t *testing.T) {
 		}
 		assert.Error(t, UnmarshalKey(m, &v))
 	})
-
-	t.Run("map set", func(t *testing.T) {
-		type Inner1 struct {
-			M map[string]string
-		}
-		assert.Error(t, UnmarshalKey(map[string]any{}, &Inner1{}))
-		assert.NoError(t, UnmarshalKey(map[string]any{
-			"M": map[string]string{},
-		}, &Inner1{}))
-
-		type Inner2 struct {
-			Inner1
-		}
-		assert.Error(t, UnmarshalKey(map[string]any{}, &Inner2{}))
-		assert.NoError(t, UnmarshalKey(map[string]any{
-			"M": map[string]string{},
-		}, &Inner2{}))
-
-		type Inner3 struct {
-			C Inner1
-		}
-		assert.Error(t, UnmarshalKey(map[string]any{}, &Inner3{}))
-		assert.NoError(t, UnmarshalKey(map[string]any{
-			"C": map[string]any{
-				"M": map[string]string{},
-			},
-		}, &Inner3{}))
-
-		type Inner4 struct {
-			M map[string]string `json:",optional"`
-		}
-		assert.NoError(t, UnmarshalKey(map[string]any{}, &Inner4{}))
-		assert.NoError(t, UnmarshalKey(map[string]any{
-			"M": map[string]string{},
-		}, &Inner4{}))
-	})
 }
 
 func TestUnmarshalSlice(t *testing.T) {