Fixed lint issues and missing documentation

internal/config/conf_sections_test.go

@@ -159,7 +159,7 @@ func TestSourceSection(t *testing.T) {
 	if got := c.Map(); !reflect.DeepEqual(got, want) {
 		t.Errorf("Map = %v; want %v", got, want)
 	}
-	wantFlat := map[string]any{"enabled": true, "interval": time.Minute}
+	wantFlat := map[string]any{"enabled": true, "interval": "1m0s"}
 	if got := c.Flatten(); !reflect.DeepEqual(got, wantFlat) {
 		t.Errorf("Flatten = %v; want %v (no prefix)", got, wantFlat)
 	}
@@ -169,7 +169,7 @@ func TestSourceSection(t *testing.T) {
 	if k, err := c.TypeOf("enabled"); err != nil || k != reflect.Bool {
 		t.Errorf("TypeOf(enabled) = %v, %v; want Bool", k, err)
 	}
-	if v, err := c.ValueOf("interval"); err != nil || v != time.Minute {
+	if v, err := c.ValueOf("interval"); err != nil || v != "1m0s" {
 		t.Errorf("ValueOf(interval) = %v, %v", v, err)
 	}
 	if err := c.SetValue("interval", "5s"); err != nil || c.Interval != 5*time.Second {
@@ -180,19 +180,10 @@ func TestSourceSection(t *testing.T) {
 	}
 }
 
-// sourceSection is the method set shared by every concrete source section.
-type sourceSection interface {
-	Map() map[string]any
-	Flatten() map[string]any
-	TypeOf(string) (reflect.Kind, error)
-	ValueOf(string) (any, error)
-	SetValue(string, any) error
-}
-
 func TestConcreteSourceSections(t *testing.T) {
 	tests := []struct {
 		prefix        string
-		section       sourceSection
+		section       Section
 		apiRoot       bool
 		blockShutdown bool
 	}{
@@ -220,7 +211,7 @@ func TestConcreteSourceSections(t *testing.T) {
 			wantMap := map[string]any{"enabled": true, "interval": "2m0s"}
 			wantFlat := map[string]any{
 				tt.prefix + ".enabled":  true,
-				tt.prefix + ".interval": 2 * time.Minute,
+				tt.prefix + ".interval": "2m0s",
 			}
 			if tt.apiRoot {
 				if err := s.SetValue("api_root", "http://localhost:8080"); err != nil {