context list: remove temporary ContextType from JSON output

This reverts commit fed9fa0f72.

This removes the ContextType field, which was temporarily added to provide
compatibility with the "compose-cli" wrapper that shipped with Docker Desktop.
The compose-cli wrapper extended the context struct with an additional field
that was not part of the CLI itself, but was used by Visual Studio to detect
the type of context.

This temporary field shipped as part of Docker 27.0 June 2024), which should
be enough time for Visual Studio to have adjusted their integration.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

cli/command/formatter/context.go

@@ -1,7 +1,5 @@
 package formatter
 
-import "encoding/json"
-
 const (
 	// ClientContextTableFormat is the default client context format.
 	ClientContextTableFormat = "table {{.Name}}{{if .Current}} *{{end}}\t{{.Description}}\t{{.DockerEndpoint}}\t{{.Error}}"
@@ -30,13 +28,6 @@ type ClientContext struct {
 	DockerEndpoint string
 	Current        bool
 	Error          string
-
-	// ContextType is a temporary field for compatibility with
-	// Visual Studio, which depends on this from the "cloud integration"
-	// wrapper.
-	//
-	// Deprecated: this type is only for backward-compatibility. Do not use.
-	ContextType string `json:"ContextType,omitempty"`
 }
 
 // ClientContextWrite writes formatted contexts using the Context
@@ -69,13 +60,6 @@ func newClientContextContext() *clientContextContext {
 }
 
 func (c *clientContextContext) MarshalJSON() ([]byte, error) {
-	if c.c.ContextType != "" {
-		// We only have ContextType set for plain "json" or "{{json .}}" formatting,
-		// so we should be able to just use the default json.Marshal with no
-		// special handling.
-		return json.Marshal(c.c)
-	}
-	// FIXME(thaJeztah): why do we need a special marshal function here?
 	return MarshalJSON(c)
 }