diff --git a/go.mod b/go.mod
index 8806a7a..3ba7b06 100644
--- a/go.mod
+++ b/go.mod
@@ -11,26 +11,26 @@ require (
 	github.com/go-viper/encoding/toml v0.1.0
 	github.com/go-viper/encoding/yaml v0.1.0
 	github.com/go-viper/mapstructure/v2 v2.0.0
-	github.com/hashicorp/hcl v1.0.0
-	github.com/magiconair/properties v1.8.7
-	github.com/pelletier/go-toml/v2 v2.2.2
 	github.com/sagikazarmark/locafero v0.6.0
 	github.com/spf13/afero v1.11.0
 	github.com/spf13/cast v1.6.0
 	github.com/spf13/pflag v1.0.5
 	github.com/stretchr/testify v1.9.0
-	github.com/subosito/gotenv v1.6.0
-	gopkg.in/ini.v1 v1.67.0
-	gopkg.in/yaml.v3 v3.0.1
 )
 
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/google/go-cmp v0.6.0 // indirect
+	github.com/hashicorp/hcl v1.0.0 // indirect
+	github.com/magiconair/properties v1.8.7 // indirect
+	github.com/pelletier/go-toml/v2 v2.2.2 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/sourcegraph/conc v0.3.0 // indirect
+	github.com/subosito/gotenv v1.6.0 // indirect
 	go.uber.org/atomic v1.9.0 // indirect
 	go.uber.org/multierr v1.9.0 // indirect
 	golang.org/x/sys v0.20.0 // indirect
 	golang.org/x/text v0.15.0 // indirect
+	gopkg.in/ini.v1 v1.67.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
diff --git a/internal/encoding/dotenv/codec.go b/internal/encoding/dotenv/codec.go
deleted file mode 100644
index 3ebc76f..0000000
--- a/internal/encoding/dotenv/codec.go
+++ /dev/null
@@ -1,61 +0,0 @@
-package dotenv
-
-import (
-	"bytes"
-	"fmt"
-	"sort"
-	"strings"
-
-	"github.com/subosito/gotenv"
-)
-
-const keyDelimiter = "_"
-
-// Codec implements the encoding.Encoder and encoding.Decoder interfaces for encoding data containing environment variables
-// (commonly called as dotenv format).
-type Codec struct{}
-
-func (Codec) Encode(v map[string]any) ([]byte, error) {
-	flattened := map[string]any{}
-
-	flattened = flattenAndMergeMap(flattened, v, "", keyDelimiter)
-
-	keys := make([]string, 0, len(flattened))
-
-	for key := range flattened {
-		keys = append(keys, key)
-	}
-
-	sort.Strings(keys)
-
-	var buf bytes.Buffer
-
-	for _, key := range keys {
-		_, err := buf.WriteString(fmt.Sprintf("%v=%v\n", strings.ToUpper(key), flattened[key]))
-		if err != nil {
-			return nil, err
-		}
-	}
-
-	return buf.Bytes(), nil
-}
-
-func (Codec) Decode(b []byte, v map[string]any) error {
-	var buf bytes.Buffer
-
-	_, err := buf.Write(b)
-	if err != nil {
-		return err
-	}
-
-	env, err := gotenv.StrictParse(&buf)
-	if err != nil {
-		return err
-	}
-
-	for key, value := range env {
-		v[key] = value
-	}
-
-	return nil
-}
diff --git a/internal/encoding/dotenv/codec_test.go b/internal/encoding/dotenv/codec_test.go
deleted file mode 100644
index ac2257b..0000000
--- a/internal/encoding/dotenv/codec_test.go
+++ /dev/null
@@ -1,55 +0,0 @@
-package dotenv
-
-import (
-	"testing"
-
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-)
-
-// original form of the data.
-const original = `# key-value pair
-KEY=value
-`
-
-// encoded form of the data.
-const encoded = `KEY=value
-`
-
-// data is Viper's internal representation.
-var data = map[string]any{
-	"KEY": "value",
-}
-
-func TestCodec_Encode(t *testing.T) {
-	codec := Codec{}
-
-	b, err := codec.Encode(data)
-	require.NoError(t, err)
-
-	assert.Equal(t, encoded, string(b))
-}
-
-func TestCodec_Decode(t *testing.T) {
-	t.Run("OK", func(t *testing.T) {
-		codec := Codec{}
-
-		v := map[string]any{}
-
-		err := codec.Decode([]byte(original), v)
-		require.NoError(t, err)
-
-		assert.Equal(t, data, v)
-	})
-
-	t.Run("InvalidData", func(t *testing.T) {
-		codec := Codec{}
-
-		v := map[string]any{}
-
-		err := codec.Decode([]byte(`invalid data`), v)
-		require.Error(t, err)
-
-		t.Logf("decoding failed as expected: %s", err)
-	})
-}
diff --git a/internal/encoding/dotenv/map_utils.go b/internal/encoding/dotenv/map_utils.go
deleted file mode 100644
index 8bfe0a9..0000000
--- a/internal/encoding/dotenv/map_utils.go
+++ /dev/null
@@ -1,41 +0,0 @@
-package dotenv
-
-import (
-	"strings"
-
-	"github.com/spf13/cast"
-)
-
-// flattenAndMergeMap recursively flattens the given map into a new map
-// Code is based on the function with the same name in the main package.
-// TODO: move it to a common place.
-func flattenAndMergeMap(shadow, m map[string]any, prefix, delimiter string) map[string]any {
-	if shadow != nil && prefix != "" && shadow[prefix] != nil {
-		// prefix is shadowed => nothing more to flatten
-		return shadow
-	}
-	if shadow == nil {
-		shadow = make(map[string]any)
-	}
-
-	var m2 map[string]any
-	if prefix != "" {
-		prefix += delimiter
-	}
-	for k, val := range m {
-		fullKey := prefix + k
-		switch val := val.(type) {
-		case map[string]any:
-			m2 = val
-		case map[any]any:
-			m2 = cast.ToStringMap(val)
-		default:
-			// immediate value
-			shadow[strings.ToLower(fullKey)] = val
-			continue
-		}
-		// recursively merge to shadow map
-		shadow = flattenAndMergeMap(shadow, m2, fullKey, delimiter)
-	}
-	return shadow
-}
diff --git a/internal/encoding/hcl/codec.go b/internal/encoding/hcl/codec.go
deleted file mode 100644
index d7fa8a1..0000000
--- a/internal/encoding/hcl/codec.go
+++ /dev/null
@@ -1,40 +0,0 @@
-package hcl
-
-import (
-	"bytes"
-	"encoding/json"
-
-	"github.com/hashicorp/hcl"
-	"github.com/hashicorp/hcl/hcl/printer"
-)
-
-// Codec implements the encoding.Encoder and encoding.Decoder interfaces for HCL encoding.
-// TODO: add printer config to the codec?
-type Codec struct{}
-
-func (Codec) Encode(v map[string]any) ([]byte, error) {
-	b, err := json.Marshal(v)
-	if err != nil {
-		return nil, err
-	}
-
-	// TODO: use printer.Format? Is the trailing newline an issue?
-
-	ast, err := hcl.Parse(string(b))
-	if err != nil {
-		return nil, err
-	}
-
-	var buf bytes.Buffer
-
-	err = printer.Fprint(&buf, ast.Node)
-	if err != nil {
-		return nil, err
-	}
-
-	return buf.Bytes(), nil
-}
-
-func (Codec) Decode(b []byte, v map[string]any) error {
-	return hcl.Unmarshal(b, &v)
-}
diff --git a/internal/encoding/hcl/codec_test.go b/internal/encoding/hcl/codec_test.go
deleted file mode 100644
index b1d2d5a..0000000
--- a/internal/encoding/hcl/codec_test.go
+++ /dev/null
@@ -1,132 +0,0 @@
-package hcl
-
-import (
-	"testing"
-
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-)
-
-// original form of the data.
-const original = `# key-value pair
-"key" = "value"
-
-// list
-"list" = ["item1", "item2", "item3"]
-
-/* map */
-"map" = {
-  "key" = "value"
-}
-
-/*
-nested map
-*/
-"nested_map" "map" {
-  "key" = "value"
-
-  "list" = ["item1", "item2", "item3"]
-}`
-
-// encoded form of the data.
-const encoded = `"key" = "value"
-
-"list" = ["item1", "item2", "item3"]
-
-"map" = {
-  "key" = "value"
-}
-
-"nested_map" "map" {
-  "key" = "value"
-
-  "list" = ["item1", "item2", "item3"]
-}`
-
-// decoded form of the data.
-//
-// In case of HCL it's slightly different from Viper's internal representation
-// (e.g. map is decoded into a list of maps).
-var decoded = map[string]any{
-	"key": "value",
-	"list": []any{
-		"item1",
-		"item2",
-		"item3",
-	},
-	"map": []map[string]any{
-		{
-			"key": "value",
-		},
-	},
-	"nested_map": []map[string]any{
-		{
-			"map": []map[string]any{
-				{
-					"key": "value",
-					"list": []any{
-						"item1",
-						"item2",
-						"item3",
-					},
-				},
-			},
-		},
-	},
-}
-
-// data is Viper's internal representation.
-var data = map[string]any{
-	"key": "value",
-	"list": []any{
-		"item1",
-		"item2",
-		"item3",
-	},
-	"map": map[string]any{
-		"key": "value",
-	},
-	"nested_map": map[string]any{
-		"map": map[string]any{
-			"key": "value",
-			"list": []any{
-				"item1",
-				"item2",
-				"item3",
-			},
-		},
-	},
-}
-
-func TestCodec_Encode(t *testing.T) {
-	codec := Codec{}
-
-	b, err := codec.Encode(data)
-	require.NoError(t, err)
-
-	assert.Equal(t, encoded, string(b))
-}
-
-func TestCodec_Decode(t *testing.T) {
-	t.Run("OK", func(t *testing.T) {
-		codec := Codec{}
-
-		v := map[string]any{}
-
-		err := codec.Decode([]byte(original), v)
-		require.NoError(t, err)
-
-		assert.Equal(t, decoded, v)
-	})
-
-	t.Run("InvalidData", func(t *testing.T) {
-		codec := Codec{}
-
-		v := map[string]any{}
-
-		err := codec.Decode([]byte(`invalid data`), v)
-		require.Error(t, err)
-
-		t.Logf("decoding failed as expected: %s", err)
-	})
-}
diff --git a/internal/encoding/ini/codec.go b/internal/encoding/ini/codec.go
deleted file mode 100644
index d91cf59..0000000
--- a/internal/encoding/ini/codec.go
+++ /dev/null
@@ -1,99 +0,0 @@
-package ini
-
-import (
-	"bytes"
-	"sort"
-	"strings"
-
-	"github.com/spf13/cast"
-	"gopkg.in/ini.v1"
-)
-
-// LoadOptions contains all customized options used for load data source(s).
-// This type is added here for convenience: this way consumers can import a single package called "ini".
-type LoadOptions = ini.LoadOptions
-
-// Codec implements the encoding.Encoder and encoding.Decoder interfaces for INI encoding.
-type Codec struct {
-	KeyDelimiter string
-	LoadOptions  LoadOptions
-}
-
-func (c Codec) Encode(v map[string]any) ([]byte, error) {
-	cfg := ini.Empty()
-	ini.PrettyFormat = false
-
-	flattened := map[string]any{}
-
-	flattened = flattenAndMergeMap(flattened, v, "", c.keyDelimiter())
-
-	keys := make([]string, 0, len(flattened))
-
-	for key := range flattened {
-		keys = append(keys, key)
-	}
-
-	sort.Strings(keys)
-
-	for _, key := range keys {
-		sectionName, keyName := "", key
-
-		lastSep := strings.LastIndex(key, ".")
-		if lastSep != -1 {
-			sectionName = key[:(lastSep)]
-			keyName = key[(lastSep + 1):]
-		}
-
-		// TODO: is this a good idea?
-		if sectionName == "default" {
-			sectionName = ""
-		}
-
-		cfg.Section(sectionName).Key(keyName).SetValue(cast.ToString(flattened[key]))
-	}
-
-	var buf bytes.Buffer
-
-	_, err := cfg.WriteTo(&buf)
-	if err != nil {
-		return nil, err
-	}
-
-	return buf.Bytes(), nil
-}
-
-func (c Codec) Decode(b []byte, v map[string]any) error {
-	cfg := ini.Empty(c.LoadOptions)
-
-	err := cfg.Append(b)
-	if err != nil {
-		return err
-	}
-
-	sections := cfg.Sections()
-
-	for i := 0; i < len(sections); i++ {
-		section := sections[i]
-		keys := section.Keys()
-
-		for j := 0; j < len(keys); j++ {
-			key := keys[j]
-			value := cfg.Section(section.Name()).Key(key.Name()).String()
-
-			deepestMap := deepSearch(v, strings.Split(section.Name(), c.keyDelimiter()))
-
-			// set innermost value
-			deepestMap[key.Name()] = value
-		}
-	}
-
-	return nil
-}
-
-func (c Codec) keyDelimiter() string {
-	if c.KeyDelimiter == "" {
-		return "."
-	}
-
-	return c.KeyDelimiter
-}
diff --git a/internal/encoding/ini/codec_test.go b/internal/encoding/ini/codec_test.go
deleted file mode 100644
index f9d9e70..0000000
--- a/internal/encoding/ini/codec_test.go
+++ /dev/null
@@ -1,99 +0,0 @@
-package ini
-
-import (
-	"testing"
-
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-)
-
-// original form of the data.
-const original = `; key-value pair
-key=value ; key-value pair
-
-# map
-[map] # map
-key=%(key)s
-
-`
-
-// encoded form of the data.
-const encoded = `key=value
-
-[map]
-key=value
-`
-
-// decoded form of the data.
-//
-// In case of INI it's slightly different from Viper's internal representation
-// (e.g. top level keys land in a section called default).
-var decoded = map[string]any{
-	"DEFAULT": map[string]any{
-		"key": "value",
-	},
-	"map": map[string]any{
-		"key": "value",
-	},
-}
-
-// data is Viper's internal representation.
-var data = map[string]any{
-	"key": "value",
-	"map": map[string]any{
-		"key": "value",
-	},
-}
-
-func TestCodec_Encode(t *testing.T) {
-	t.Run("OK", func(t *testing.T) {
-		codec := Codec{}
-
-		b, err := codec.Encode(data)
-		require.NoError(t, err)
-
-		assert.Equal(t, encoded, string(b))
-	})
-
-	t.Run("Default", func(t *testing.T) {
-		codec := Codec{}
-
-		data := map[string]any{
-			"default": map[string]any{
-				"key": "value",
-			},
-			"map": map[string]any{
-				"key": "value",
-			},
-		}
-
-		b, err := codec.Encode(data)
-		require.NoError(t, err)
-
-		assert.Equal(t, encoded, string(b))
-	})
-}
-
-func TestCodec_Decode(t *testing.T) {
-	t.Run("OK", func(t *testing.T) {
-		codec := Codec{}
-
-		v := map[string]any{}
-
-		err := codec.Decode([]byte(original), v)
-		require.NoError(t, err)
-
-		assert.Equal(t, decoded, v)
-	})
-
-	t.Run("InvalidData", func(t *testing.T) {
-		codec := Codec{}
-
-		v := map[string]any{}
-
-		err := codec.Decode([]byte(`invalid data`), v)
-		require.Error(t, err)
-
-		t.Logf("decoding failed as expected: %s", err)
-	})
-}
diff --git a/internal/encoding/ini/map_utils.go b/internal/encoding/ini/map_utils.go
deleted file mode 100644
index 490ab59..0000000
--- a/internal/encoding/ini/map_utils.go
+++ /dev/null
@@ -1,74 +0,0 @@
-package ini
-
-import (
-	"strings"
-
-	"github.com/spf13/cast"
-)
-
-// THIS CODE IS COPIED HERE: IT SHOULD NOT BE MODIFIED
-// AT SOME POINT IT WILL BE MOVED TO A COMMON PLACE
-// deepSearch scans deep maps, following the key indexes listed in the
-// sequence "path".
-// The last value is expected to be another map, and is returned.
-//
-// In case intermediate keys do not exist, or map to a non-map value,
-// a new map is created and inserted, and the search continues from there:
-// the initial map "m" may be modified!
-func deepSearch(m map[string]any, path []string) map[string]any {
-	for _, k := range path {
-		m2, ok := m[k]
-		if !ok {
-			// intermediate key does not exist
-			// => create it and continue from there
-			m3 := make(map[string]any)
-			m[k] = m3
-			m = m3
-			continue
-		}
-		m3, ok := m2.(map[string]any)
-		if !ok {
-			// intermediate key is a value
-			// => replace with a new map
-			m3 = make(map[string]any)
-			m[k] = m3
-		}
-		// continue search from here
-		m = m3
-	}
-	return m
-}
-
-// flattenAndMergeMap recursively flattens the given map into a new map
-// Code is based on the function with the same name in the main package.
-// TODO: move it to a common place.
-func flattenAndMergeMap(shadow, m map[string]any, prefix, delimiter string) map[string]any {
-	if shadow != nil && prefix != "" && shadow[prefix] != nil {
-		// prefix is shadowed => nothing more to flatten
-		return shadow
-	}
-	if shadow == nil {
-		shadow = make(map[string]any)
-	}
-
-	var m2 map[string]any
-	if prefix != "" {
-		prefix += delimiter
-	}
-	for k, val := range m {
-		fullKey := prefix + k
-		switch val := val.(type) {
-		case map[string]any:
-			m2 = val
-		case map[any]any:
-			m2 = cast.ToStringMap(val)
-		default:
-			// immediate value
-			shadow[strings.ToLower(fullKey)] = val
-			continue
-		}
-		// recursively merge to shadow map
-		shadow = flattenAndMergeMap(shadow, m2, fullKey, delimiter)
-	}
-	return shadow
-}
diff --git a/internal/encoding/javaproperties/codec.go b/internal/encoding/javaproperties/codec.go
deleted file mode 100644
index e92e517..0000000
--- a/internal/encoding/javaproperties/codec.go
+++ /dev/null
@@ -1,86 +0,0 @@
-package javaproperties
-
-import (
-	"bytes"
-	"sort"
-	"strings"
-
-	"github.com/magiconair/properties"
-	"github.com/spf13/cast"
-)
-
-// Codec implements the encoding.Encoder and encoding.Decoder interfaces for Java properties encoding.
-type Codec struct {
-	KeyDelimiter string
-
-	// Store read properties on the object so that we can write back in order with comments.
-	// This will only be used if the configuration read is a properties file.
-	// TODO: drop this feature in v2
-	// TODO: make use of the global properties object optional
-	Properties *properties.Properties
-}
-
-func (c *Codec) Encode(v map[string]any) ([]byte, error) {
-	if c.Properties == nil {
-		c.Properties = properties.NewProperties()
-	}
-
-	flattened := map[string]any{}
-
-	flattened = flattenAndMergeMap(flattened, v, "", c.keyDelimiter())
-
-	keys := make([]string, 0, len(flattened))
-
-	for key := range flattened {
-		keys = append(keys, key)
-	}
-
-	sort.Strings(keys)
-
-	for _, key := range keys {
-		_, _, err := c.Properties.Set(key, cast.ToString(flattened[key]))
-		if err != nil {
-			return nil, err
-		}
-	}
-
-	var buf bytes.Buffer
-
-	_, err := c.Properties.WriteComment(&buf, "#", properties.UTF8)
-	if err != nil {
-		return nil, err
-	}
-
-	return buf.Bytes(), nil
-}
-
-func (c *Codec) Decode(b []byte, v map[string]any) error {
-	var err error
-	c.Properties, err = properties.Load(b, properties.UTF8)
-	if err != nil {
-		return err
-	}
-
-	for _, key := range c.Properties.Keys() {
-		// ignore existence check: we know it's there
-		value, _ := c.Properties.Get(key)
-
-		// recursively build nested maps
-		path := strings.Split(key, c.keyDelimiter())
-		lastKey := strings.ToLower(path[len(path)-1])
-		deepestMap := deepSearch(v, path[0:len(path)-1])
-
-		// set innermost value
-		deepestMap[lastKey] = value
-	}
-
-	return nil
-}
-
-func (c Codec) keyDelimiter() string {
-	if c.KeyDelimiter == "" {
-		return "."
-	}
-
-	return c.KeyDelimiter
-}
diff --git a/internal/encoding/javaproperties/codec_test.go b/internal/encoding/javaproperties/codec_test.go
deleted file mode 100644
index ab5aec0..0000000
--- a/internal/encoding/javaproperties/codec_test.go
+++ /dev/null
@@ -1,75 +0,0 @@
-package javaproperties
-
-import (
-	"testing"
-
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-)
-
-// original form of the data.
-const original = `#key-value pair
-key = value
-map.key = value
-`
-
-// encoded form of the data.
-const encoded = `key = value
-map.key = value
-`
-
-// data is Viper's internal representation.
-var data = map[string]any{
-	"key": "value",
-	"map": map[string]any{
-		"key": "value",
-	},
-}
-
-func TestCodec_Encode(t *testing.T) {
-	codec := Codec{}
-
-	b, err := codec.Encode(data)
-	require.NoError(t, err)
-
-	assert.Equal(t, encoded, string(b))
-}
-
-func TestCodec_Decode(t *testing.T) {
-	t.Run("OK", func(t *testing.T) {
-		codec := Codec{}
-
-		v := map[string]any{}
-
-		err := codec.Decode([]byte(original), v)
-		require.NoError(t, err)
-
-		assert.Equal(t, data, v)
-	})
-
-	t.Run("InvalidData", func(t *testing.T) {
-		t.Skip("TODO: needs invalid data example")
-
-		codec := Codec{}
-
-		v := map[string]any{}
-
-		codec.Decode([]byte(``), v)
-
-		assert.Empty(t, v)
-	})
-}
-
-func TestCodec_DecodeEncode(t *testing.T) {
-	codec := Codec{}
-
-	v := map[string]any{}
-
-	err := codec.Decode([]byte(original), v)
-	require.NoError(t, err)
-
-	b, err := codec.Encode(data)
-	require.NoError(t, err)
-
-	assert.Equal(t, original, string(b))
-}
diff --git a/internal/encoding/javaproperties/map_utils.go b/internal/encoding/javaproperties/map_utils.go
deleted file mode 100644
index 6e1aff2..0000000
--- a/internal/encoding/javaproperties/map_utils.go
+++ /dev/null
@@ -1,74 +0,0 @@
-package javaproperties
-
-import (
-	"strings"
-
-	"github.com/spf13/cast"
-)
-
-// THIS CODE IS COPIED HERE: IT SHOULD NOT BE MODIFIED
-// AT SOME POINT IT WILL BE MOVED TO A COMMON PLACE
-// deepSearch scans deep maps, following the key indexes listed in the
-// sequence "path".
-// The last value is expected to be another map, and is returned.
-//
-// In case intermediate keys do not exist, or map to a non-map value,
-// a new map is created and inserted, and the search continues from there:
-// the initial map "m" may be modified!
-func deepSearch(m map[string]any, path []string) map[string]any {
-	for _, k := range path {
-		m2, ok := m[k]
-		if !ok {
-			// intermediate key does not exist
-			// => create it and continue from there
-			m3 := make(map[string]any)
-			m[k] = m3
-			m = m3
-			continue
-		}
-		m3, ok := m2.(map[string]any)
-		if !ok {
-			// intermediate key is a value
-			// => replace with a new map
-			m3 = make(map[string]any)
-			m[k] = m3
-		}
-		// continue search from here
-		m = m3
-	}
-	return m
-}
-
-// flattenAndMergeMap recursively flattens the given map into a new map
-// Code is based on the function with the same name in the main package.
-// TODO: move it to a common place.
-func flattenAndMergeMap(shadow, m map[string]any, prefix, delimiter string) map[string]any {
-	if shadow != nil && prefix != "" && shadow[prefix] != nil {
-		// prefix is shadowed => nothing more to flatten
-		return shadow
-	}
-	if shadow == nil {
-		shadow = make(map[string]any)
-	}
-
-	var m2 map[string]any
-	if prefix != "" {
-		prefix += delimiter
-	}
-	for k, val := range m {
-		fullKey := prefix + k
-		switch val := val.(type) {
-		case map[string]any:
-			m2 = val
-		case map[any]any:
-			m2 = cast.ToStringMap(val)
-		default:
-			// immediate value
-			shadow[strings.ToLower(fullKey)] = val
-			continue
-		}
-		// recursively merge to shadow map
-		shadow = flattenAndMergeMap(shadow, m2, fullKey, delimiter)
-	}
-	return shadow
-}
diff --git a/internal/encoding/toml/codec.go b/internal/encoding/toml/codec.go
deleted file mode 100644
index c70aa8d..0000000
--- a/internal/encoding/toml/codec.go
+++ /dev/null
@@ -1,16 +0,0 @@
-package toml
-
-import (
-	"github.com/pelletier/go-toml/v2"
-)
-
-// Codec implements the encoding.Encoder and encoding.Decoder interfaces for TOML encoding.
-type Codec struct{}
-
-func (Codec) Encode(v map[string]any) ([]byte, error) {
-	return toml.Marshal(v)
-}
-
-func (Codec) Decode(b []byte, v map[string]any) error {
-	return toml.Unmarshal(b, &v)
-}
diff --git a/internal/encoding/toml/codec_test.go b/internal/encoding/toml/codec_test.go
deleted file mode 100644
index 91d9e13..0000000
--- a/internal/encoding/toml/codec_test.go
+++ /dev/null
@@ -1,97 +0,0 @@
-package toml
-
-import (
-	"testing"
-
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-)
-
-// original form of the data.
-const original = `# key-value pair
-key = "value"
-list = ["item1", "item2", "item3"]
-
-[map]
-key = "value"
-
-# nested
-# map
-[nested_map]
-[nested_map.map]
-key = "value"
-list = [
-  "item1",
-  "item2",
-  "item3",
-]
-`
-
-// encoded form of the data.
-const encoded = `key = 'value'
-list = ['item1', 'item2', 'item3']
-
-[map]
-key = 'value'
-
-[nested_map]
-[nested_map.map]
-key = 'value'
-list = ['item1', 'item2', 'item3']
-`
-
-// data is Viper's internal representation.
-var data = map[string]any{
-	"key": "value",
-	"list": []any{
-		"item1",
-		"item2",
-		"item3",
-	},
-	"map": map[string]any{
-		"key": "value",
-	},
-	"nested_map": map[string]any{
-		"map": map[string]any{
-			"key": "value",
-			"list": []any{
-				"item1",
-				"item2",
-				"item3",
-			},
-		},
-	},
-}
-
-func TestCodec_Encode(t *testing.T) {
-	codec := Codec{}
-
-	b, err := codec.Encode(data)
-	require.NoError(t, err)
-
-	assert.Equal(t, encoded, string(b))
-}
-
-func TestCodec_Decode(t *testing.T) {
-	t.Run("OK", func(t *testing.T) {
-		codec := Codec{}
-
-		v := map[string]any{}
-
-		err := codec.Decode([]byte(original), v)
-		require.NoError(t, err)
-
-		assert.Equal(t, data, v)
-	})
-
-	t.Run("InvalidData", func(t *testing.T) {
-		codec := Codec{}
-
-		v := map[string]any{}
-
-		err := codec.Decode([]byte(`invalid data`), v)
-		require.Error(t, err)
-
-		t.Logf("decoding failed as expected: %s", err)
-	})
-}
diff --git a/internal/encoding/yaml/codec.go b/internal/encoding/yaml/codec.go
deleted file mode 100644
index 0368792..0000000
--- a/internal/encoding/yaml/codec.go
+++ /dev/null
@@ -1,14 +0,0 @@
-package yaml
-
-import "gopkg.in/yaml.v3"
-
-// Codec implements the encoding.Encoder and encoding.Decoder interfaces for YAML encoding.
-type Codec struct{}
-
-func (Codec) Encode(v map[string]any) ([]byte, error) {
-	return yaml.Marshal(v)
-}
-
-func (Codec) Decode(b []byte, v map[string]any) error {
-	return yaml.Unmarshal(b, &v)
-}
diff --git a/internal/encoding/yaml/codec_test.go b/internal/encoding/yaml/codec_test.go
deleted file mode 100644
index 2d2d8ba..0000000
--- a/internal/encoding/yaml/codec_test.go
+++ /dev/null
@@ -1,128 +0,0 @@
-package yaml
-
-import (
-	"testing"
-
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-)
-
-// original form of the data.
-const original = `# key-value pair
-key: value
-list:
-    - item1
-    - item2
-    - item3
-map:
-    key: value
-
-# nested
-# map
-nested_map:
-    map:
-        key: value
-        list:
-            - item1
-            - item2
-            - item3
-`
-
-// encoded form of the data.
-const encoded = `key: value
-list:
-    - item1
-    - item2
-    - item3
-map:
-    key: value
-nested_map:
-    map:
-        key: value
-        list:
-            - item1
-            - item2
-            - item3
-`
-
-// decoded form of the data.
-//
-// In case of YAML it's slightly different from Viper's internal representation
-// (e.g. map is decoded into a map with interface key).
-var decoded = map[string]any{
-	"key": "value",
-	"list": []any{
-		"item1",
-		"item2",
-		"item3",
-	},
-	"map": map[string]any{
-		"key": "value",
-	},
-	"nested_map": map[string]any{
-		"map": map[string]any{
-			"key": "value",
-			"list": []any{
-				"item1",
-				"item2",
-				"item3",
-			},
-		},
-	},
-}
-
-// data is Viper's internal representation.
-var data = map[string]any{
-	"key": "value",
-	"list": []any{
-		"item1",
-		"item2",
-		"item3",
-	},
-	"map": map[string]any{
-		"key": "value",
-	},
-	"nested_map": map[string]any{
-		"map": map[string]any{
-			"key": "value",
-			"list": []any{
-				"item1",
-				"item2",
-				"item3",
-			},
-		},
-	},
-}
-
-func TestCodec_Encode(t *testing.T) {
-	codec := Codec{}
-
-	b, err := codec.Encode(data)
-	require.NoError(t, err)
-
-	assert.Equal(t, encoded, string(b))
-}
-
-func TestCodec_Decode(t *testing.T) {
-	t.Run("OK", func(t *testing.T) {
-		codec := Codec{}
-
-		v := map[string]any{}
-
-		err := codec.Decode([]byte(original), v)
-		require.NoError(t, err)
-
-		assert.Equal(t, decoded, v)
-	})
-
-	t.Run("InvalidData", func(t *testing.T) {
-		codec := Codec{}
-
-		v := map[string]any{}
-
-		err := codec.Decode([]byte(`invalid data`), v)
-		require.Error(t, err)
-
-		t.Logf("decoding failed as expected: %s", err)
-	})
-}