[confmap] Remove deprecated confmap.WithErrorUnused (#9503)

**Description:**
Remove deprecated `confmap.WithErrorUnused`

**Link to tracking Issue:**
Fixes #9484

---------

Co-authored-by: Pablo Baeyens <pablo.baeyens@datadoghq.com>
Co-authored-by: Pablo Baeyens <pbaeyens31+github@gmail.com>

.chloggen/remove_withErrorUnused.yaml

@@ -0,0 +1,25 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: breaking
+
+# The name of the component, or a single word describing the area of concern, (e.g. otlpreceiver)
+component: confmap
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Remove deprecated `confmap.WithErrorUnused`
+
+# One or more tracking issues or pull requests related to the change
+issues: [9484]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [api]

cmd/mdatagen/loader.go

@@ -124,7 +124,7 @@ func (m *metric) Unmarshal(parser *confmap.Conf) error {
 	if !parser.IsSet("enabled") {
 		return errors.New("missing required field: `enabled`")
 	}
-	err := parser.Unmarshal(m, confmap.WithErrorUnused())
+	err := parser.Unmarshal(m)
 	if err != nil {
 		return err
 	}
@@ -253,7 +253,7 @@ func loadMetadata(filePath string) (metadata, error) {
 	}
 
 	md := metadata{ScopeName: scopeName(filePath), ShortFolderName: shortFolderName(filePath)}
-	if err := conf.Unmarshal(&md, confmap.WithErrorUnused()); err != nil {
+	if err := conf.Unmarshal(&md); err != nil {
 		return md, err
 	}
 

cmd/mdatagen/metricdata.go

@@ -125,7 +125,7 @@ func (d *gauge) Unmarshal(parser *confmap.Conf) error {
 	if err := d.MetricValueType.Unmarshal(parser); err != nil {
 		return err
 	}
-	return parser.Unmarshal(d, confmap.WithErrorUnused())
+	return parser.Unmarshal(d)
 }
 
 func (d gauge) Type() string {
@@ -155,7 +155,7 @@ func (d *sum) Unmarshal(parser *confmap.Conf) error {
 	if err := d.MetricValueType.Unmarshal(parser); err != nil {
 		return err
 	}
-	return parser.Unmarshal(d, confmap.WithErrorUnused())
+	return parser.Unmarshal(d)
 }
 
 // TODO: Currently, this func will not be called because of https://github.com/open-telemetry/opentelemetry-collector/issues/6671. Uncomment function and
@@ -166,7 +166,7 @@ func (d *sum) Unmarshal(parser *confmap.Conf) error {
 // 	if !parser.IsSet("monotonic") {
 // 		return errors.New("missing required field: `monotonic`")
 // 	}
-// 	return parser.Unmarshal(m, confmap.WithErrorUnused())
+// 	return parser.Unmarshal(m)
 // }
 
 func (d sum) Type() string {

cmd/mdatagen/templates/config.go.tmpl

@@ -19,7 +19,7 @@ func (ms *MetricConfig) Unmarshal(parser *confmap.Conf) error {
 	if parser == nil {
 		return nil
 	}
-	err := parser.Unmarshal(ms, confmap.WithErrorUnused())
+	err := parser.Unmarshal(ms)
 	if err != nil {
 		return err
 	}
@@ -57,7 +57,7 @@ func (rac *ResourceAttributeConfig) Unmarshal(parser *confmap.Conf) error {
 	if parser == nil {
 		return nil
 	}
-	err := parser.Unmarshal(rac, confmap.WithErrorUnused())
+	err := parser.Unmarshal(rac)
 	if err != nil {
 		return err
 	}

confmap/confmap.go

@@ -54,16 +54,6 @@ type unmarshalOption struct {
 	ignoreUnused bool
 }
 
-// WithErrorUnused sets an option to error when there are existing
-// keys in the original Conf that were unused in the decoding process
-// (extra keys). This option is enabled by default and can be disabled with `WithIgnoreUnused`.
-// Deprecated: [v0.92.0] this is now enabled by default. Use `WithIgnoreUnused` to disable.
-func WithErrorUnused() UnmarshalOption {
-	return unmarshalOptionFunc(func(uo *unmarshalOption) {
-		uo.ignoreUnused = false
-	})
-}
-
 // WithIgnoreUnused sets an option to ignore errors if existing
 // keys in the original Conf were unused in the decoding process
 // (extra keys).

confmap/confmap_test.go

@@ -143,7 +143,7 @@ func TestExpandNilStructPointersHookFuncDefaultNotNilConfigNil(t *testing.T) {
 	assert.Equal(t, &Struct{}, cfg.MapStruct["struct"])
 }
 
-func TestUnmarshalWithErrorUnused(t *testing.T) {
+func TestUnmarshalWithIgnoreUnused(t *testing.T) {
 	stringMap := map[string]any{
 		"boolean": true,
 		"string":  "this is a string",