Remove support for deprecated unmarshaler (#2591)

Updates #2540

Signed-off-by: Bogdan Drutu <bogdandrutu@gmail.com>

CHANGELOG.md

@@ -8,6 +8,7 @@
 - Remove `consumerdata.TraceData` (#2551)
 - Move `consumerdata.MetricsData` to `internaldata.MetricsData` (#2512)
 - Remove custom OpenCensus sematic conventions that have equivalent in otel (#2552)
+- Remove support for deprecated unmarshaler `CustomUnmarshaler`, only `Unmarshal` is supported (#2591)
 - Remove deprecated componenterror.CombineErrors (#2598)
 
 ## v0.21.0 Beta

component/componenttest/example_factories.go

@@ -73,11 +73,6 @@ func (f *ExampleReceiverFactory) CreateDefaultConfig() configmodels.Receiver {
 	}
 }
 
-// CustomUnmarshaler implements the deprecated way to provide custom unmarshalers.
-func (f *ExampleReceiverFactory) CustomUnmarshaler() component.CustomUnmarshaler {
-	return nil
-}
-
 // CreateTraceReceiver creates a trace receiver based on this config.
 func (f *ExampleReceiverFactory) CreateTracesReceiver(
 	_ context.Context,
@@ -280,11 +275,9 @@ func (f *ExampleExporterFactory) CreateDefaultConfig() configmodels.Exporter {
 	}
 }
 
-// CustomUnmarshaler implements the deprecated way to provide custom unmarshalers.
-func (f *ExampleExporterFactory) CustomUnmarshaler() component.CustomUnmarshaler {
-	return func(componentViperSection *viper.Viper, intoCfg interface{}) error {
-		return componentViperSection.UnmarshalExact(intoCfg)
-	}
+// Unmarshal implements the custom unmarshalers.
+func (f *ExampleExporterFactory) Unmarshal(componentViperSection *viper.Viper, intoCfg interface{}) error {
+	return componentViperSection.UnmarshalExact(intoCfg)
 }
 
 // CreateTracesExporter creates a trace exporter based on this config.

config/config.go

@@ -105,14 +105,6 @@ type pipelineSettings struct {
 	Exporters  []string `mapstructure:"exporters"`
 }
 
-// deprecatedUnmarshaler is the old/deprecated way to provide custom unmarshaler.
-type deprecatedUnmarshaler interface {
-	// CustomUnmarshaler returns a custom unmarshaler for the configuration or nil if
-	// there is no need for custom unmarshaling. This is typically used if viper.UnmarshalExact()
-	// is not sufficient to unmarshal correctly.
-	CustomUnmarshaler() component.CustomUnmarshaler
-}
-
 // typeAndNameSeparator is the separator that is used between type and name in type/name composite keys.
 const typeAndNameSeparator = "/"
 
@@ -736,14 +728,6 @@ func unmarshaler(factory component.Factory) component.CustomUnmarshaler {
 	if fu, ok := factory.(component.ConfigUnmarshaler); ok {
 		return fu.Unmarshal
 	}
-
-	if du, ok := factory.(deprecatedUnmarshaler); ok {
-		cu := du.CustomUnmarshaler()
-		if cu != nil {
-			return cu
-		}
-	}
-
 	return defaultUnmarshaler
 }