[chore] fix code to support unmarshaling with embedded struct support (open-telemetry#31406)

**Description:**
Code changes required to make
open-telemetry/opentelemetry-collector#9635
pass.

Author: atoulme

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)
+	return parser.Unmarshal(d, confmap.WithIgnoreUnused())
 }
 
 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)
+	return parser.Unmarshal(d, confmap.WithIgnoreUnused())
 }
 
 // TODO: Currently, this func will not be called because of https://github.com/open-telemetry/opentelemetry-collector/issues/6671. Uncomment function and

pkg/stanza/operator/config.go

@@ -107,7 +107,7 @@ func (c *Config) Unmarshal(component *confmap.Conf) error {
 	}
 
 	builder := builderFunc()
-	if err := component.Unmarshal(builder); err != nil {
+	if err := component.Unmarshal(builder, confmap.WithIgnoreUnused()); err != nil {
 		return fmt.Errorf("unmarshal to %s: %w", typeString, err)
 	}
 

pkg/stanza/operator/helper/time.go

@@ -48,7 +48,7 @@ type TimeParser struct {
 // Unmarshal starting from default settings
 func (t *TimeParser) Unmarshal(component *confmap.Conf) error {
 	cfg := NewTimeParser()
-	err := component.Unmarshal(&cfg)
+	err := component.Unmarshal(&cfg, confmap.WithIgnoreUnused())
 	if err != nil {
 		return err
 	}

pkg/stanza/operator/parser/scope/config_test.go

@@ -35,10 +35,6 @@ func TestConfig(t *testing.T) {
 					return cfg
 				}(),
 			},
-			{
-				Name:      "no_nested",
-				ExpectErr: true,
-			},
 		},
 	}.Run(t)
 }

pkg/stanza/operator/parser/severity/config_test.go

@@ -46,10 +46,6 @@ func TestUnmarshal(t *testing.T) {
 					return cfg
 				}(),
 			},
-			{
-				Name:      "no_nested",
-				ExpectErr: true,
-			},
 		},
 	}.Run(t)
 }

pkg/stanza/operator/parser/time/config_test.go

@@ -49,10 +49,6 @@ func TestUnmarshal(t *testing.T) {
 					return cfg
 				}(),
 			},
-			{
-				Name:      "no_nested",
-				ExpectErr: true,
-			},
 		},
 	}.Run(t)
 }