add optional to BuilderConfigOrderGroup struct

Author: Sophie Wigmore

cargo/jam/internal/builder_config.go

@@ -31,8 +31,9 @@ type BuilderConfigOrder struct {
 }
 
 type BuilderConfigOrderGroup struct {
-	ID      string `toml:"id"`
-	Version string `toml:"version"`
+	ID       string `toml:"id"`
+	Version  string `toml:"version"`
+	Optional bool   `toml:"optional,omitempty"`
 }
 type BuilderConfigStack struct {
 	ID              string   `toml:"id"`

cargo/jam/internal/builder_config_test.go

@@ -50,6 +50,7 @@ description = "Some description"
   [[order.group]]
     id = "some-repository/some-buildpack-id"
     version = "0.0.10"
+		optional = true
 
 [stack]
   id = "io.paketo.stacks.some-stack"
@@ -96,8 +97,9 @@ description = "Some description"
 					{
 						Group: []internal.BuilderConfigOrderGroup{
 							{
-								ID:      "some-repository/some-buildpack-id",
-								Version: "0.0.10",
+								ID:       "some-repository/some-buildpack-id",
+								Version:  "0.0.10",
+								Optional: true,
 							},
 						},
 					},

cargo/jam/update_builder_test.go

@@ -130,6 +130,7 @@ description = "Some description"
   [[order.group]]
     id = "some-repository/some-buildpack-id"
     version = "0.0.10"
+		optional = true
 
 [stack]
   id = "io.paketo.stacks.some-stack"
@@ -185,6 +186,7 @@ description = "Some description"
   [[order.group]]
     id = "some-repository/some-buildpack-id"
     version = "0.20.12"
+		optional = true
 
 [stack]
   id = "io.paketo.stacks.some-stack"