fix: regenerate proto and update converters (#81)

A lot of json-proto discrepancies were addressed in the spec repo since
we generated types from `.proto`:
* Missing `Message.ReferenceTaskIDs`.
* Missing `Part.Metadata`.
* Missing fields on `AgentCard`: `IconUrl`, `Signatures`.
* `AgentCapabilities.Security` and
`AgentCapabilities.StateTransitionHistory`.

This PR updates the spec and fixes converters.
Discrepancies were blocking the work which required Parts to have
metadata.

Author: yarolegovich

a2a/agent.go

@@ -212,7 +212,7 @@ type AgentSkill struct {
 	// As in the overall AgentCard.security, this list represents a logical OR of
 	// security requirement objects.
 	// Each object is a set of security schemes that must be used together (a logical AND).
-	Security []map[string][]string `json:"security,omitempty" yaml:"security,omitempty" mapstructure:"security,omitempty"`
+	Security []SecurityRequirements `json:"security,omitempty" yaml:"security,omitempty" mapstructure:"security,omitempty"`
 
 	// Tags is a set of keywords describing the skill's capabilities.
 	Tags []string `json:"tags" yaml:"tags" mapstructure:"tags"`

a2agrpc/handler_test.go

@@ -457,7 +457,7 @@ func TestGrpcHandler_SendMessage(t *testing.T) {
 					MessageId: "req-msg-123",
 					TaskId:    "test-task-123",
 					Role:      a2apb.Role_ROLE_USER,
-					Content: []*a2apb.Part{
+					Parts: []*a2apb.Part{
 						{
 							Part: &a2apb.Part_Text{Text: "Hello Agent"},
 						},
@@ -470,7 +470,7 @@ func TestGrpcHandler_SendMessage(t *testing.T) {
 						MessageId: "req-msg-123-response",
 						TaskId:    "test-task-123",
 						Role:      a2apb.Role_ROLE_AGENT,
-						Content: []*a2apb.Part{
+						Parts: []*a2apb.Part{
 							{
 								Part: &a2apb.Part_Text{Text: "Hello Agent"},
 							},
@@ -496,7 +496,7 @@ func TestGrpcHandler_SendMessage(t *testing.T) {
 			name: "invalid request",
 			req: &a2apb.SendMessageRequest{
 				Request: &a2apb.Message{
-					Content: []*a2apb.Part{{Part: nil}},
+					Parts: []*a2apb.Part{{Part: nil}},
 				},
 			},
 			wantErr: codes.InvalidArgument,
@@ -566,7 +566,7 @@ func TestGrpcHandler_SendStreamingMessage(t *testing.T) {
 					MessageId: msgID,
 					TaskId:    string(taskID),
 					ContextId: contextID,
-					Content:   parts,
+					Parts:     parts,
 					Role:      a2apb.Role_ROLE_USER,
 				},
 			},
@@ -595,7 +595,7 @@ func TestGrpcHandler_SendStreamingMessage(t *testing.T) {
 							MessageId: fmt.Sprintf("%s-response", msgID),
 							TaskId:    string(taskID),
 							Role:      a2apb.Role_ROLE_AGENT,
-							Content:   parts,
+							Parts:     parts,
 						},
 					},
 				},
@@ -619,7 +619,7 @@ func TestGrpcHandler_SendStreamingMessage(t *testing.T) {
 			name: "invalid request",
 			req: &a2apb.SendMessageRequest{
 				Request: &a2apb.Message{
-					Content: []*a2apb.Part{{Part: nil}},
+					Parts: []*a2apb.Part{{Part: nil}},
 				},
 			},
 			wantErr: codes.InvalidArgument,