feat: Add fromProto mappers to AgentCardMapper and dependencies

Added bidirectional mapping support for converting gRPC AgentCard to domain AgentCard.

- Added fromProto method to AgentCardMapper with conditional mapping for optional fields
- Implemented fromProto in supporting mappers: AgentCapabilitiesMapper, AgentSkillMapper, AgentExtensionMapper, AgentCardSignatureMapper
- Added polymorphic fromProto to SecuritySchemeMapper using switch expression for oneof pattern
- Implemented manual fromProto methods in concrete SecurityScheme mappers (APIKey, HTTPAuth, OAuth2, OpenIdConnect, MutualTLS) to handle immutable domain objects with constructors
- Added fromProto to OAuthFlowsMapper for OAuth2 flow conversion

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: ehsavoie

spec-grpc/src/main/java/io/a2a/grpc/mapper/APIKeySecuritySchemeMapper.java

@@ -16,4 +16,16 @@ public interface APIKeySecuritySchemeMapper {
     // location enum is converted to string via ProtoMapperConfig.map(Location)
     @Mapping(target = "description", source = "description", conditionExpression = "java(domain.getDescription() != null)")
     io.a2a.grpc.APIKeySecurityScheme toProto(io.a2a.spec.APIKeySecurityScheme domain);
+
+    default io.a2a.spec.APIKeySecurityScheme fromProto(io.a2a.grpc.APIKeySecurityScheme proto) {
+        if (proto == null) {
+            return null;
+        }
+
+        io.a2a.spec.APIKeySecurityScheme.Location location =
+            io.a2a.spec.APIKeySecurityScheme.Location.fromString(proto.getLocation());
+        String description = proto.getDescription().isEmpty() ? null : proto.getDescription();
+
+        return new io.a2a.spec.APIKeySecurityScheme(location, proto.getName(), description);
+    }
 }

spec-grpc/src/main/java/io/a2a/grpc/mapper/AgentCapabilitiesMapper.java

@@ -14,4 +14,6 @@ public interface AgentCapabilitiesMapper {
     AgentCapabilitiesMapper INSTANCE = A2AMappers.getMapper(AgentCapabilitiesMapper.class);
 
     io.a2a.grpc.AgentCapabilities toProto(io.a2a.spec.AgentCapabilities domain);
+
+    io.a2a.spec.AgentCapabilities fromProto(io.a2a.grpc.AgentCapabilities proto);
 }

spec-grpc/src/main/java/io/a2a/grpc/mapper/AgentCardMapper.java

@@ -29,4 +29,9 @@ public interface AgentCardMapper {
     @Mapping(target = "preferredTransport", ignore = true)  // Deprecated in proto, derived from supportedInterfaces[0]
     @Mapping(target = "additionalInterfaces", ignore = true)  // Deprecated in proto, use supportedInterfaces instead
     io.a2a.grpc.AgentCard toProto(io.a2a.spec.AgentCard domain);
+
+    @Mapping(target = "provider", source = "provider", conditionExpression = "java(proto.hasProvider())")
+    @Mapping(target = "documentationUrl", source = "documentationUrl", conditionExpression = "java(!proto.getDocumentationUrl().isEmpty())")
+    @Mapping(target = "iconUrl", source = "iconUrl", conditionExpression = "java(!proto.getIconUrl().isEmpty())")
+    io.a2a.spec.AgentCard fromProto(io.a2a.grpc.AgentCard proto);
 }

spec-grpc/src/main/java/io/a2a/grpc/mapper/AgentCardSignatureMapper.java

@@ -24,4 +24,13 @@ public interface AgentCardSignatureMapper {
     @Mapping(source = "protectedHeader", target = "protected")
     @Mapping(target = "header", source = "header", conditionExpression = "java(domain.header() != null)", qualifiedByName = "mapToStruct")
     io.a2a.grpc.AgentCardSignature toProto(io.a2a.spec.AgentCardSignature domain);
+
+    /**
+     * Converts proto AgentCardSignature to domain AgentCardSignature.
+     * <p>
+     * Maps protected field → protectedHeader and header from struct to map.
+     */
+    @Mapping(source = "protected", target = "protectedHeader")
+    @Mapping(target = "header", source = "header", qualifiedByName = "structToMap")
+    io.a2a.spec.AgentCardSignature fromProto(io.a2a.grpc.AgentCardSignature proto);
 }

spec-grpc/src/main/java/io/a2a/grpc/mapper/AgentExtensionMapper.java

@@ -23,4 +23,12 @@ public interface AgentExtensionMapper {
      */
     @Mapping(target = "params", source = "params", conditionExpression = "java(domain.params() != null)", qualifiedByName = "mapToStruct")
     io.a2a.grpc.AgentExtension toProto(io.a2a.spec.AgentExtension domain);
+
+    /**
+     * Converts proto AgentExtension to domain AgentExtension.
+     * <p>
+     * Maps params field from struct to map.
+     */
+    @Mapping(target = "params", source = "params", qualifiedByName = "structToMap")
+    io.a2a.spec.AgentExtension fromProto(io.a2a.grpc.AgentExtension proto);
 }

spec-grpc/src/main/java/io/a2a/grpc/mapper/AgentSkillMapper.java

@@ -14,4 +14,6 @@ public interface AgentSkillMapper {
     AgentSkillMapper INSTANCE = A2AMappers.getMapper(AgentSkillMapper.class);
 
     io.a2a.grpc.AgentSkill toProto(io.a2a.spec.AgentSkill domain);
+
+    io.a2a.spec.AgentSkill fromProto(io.a2a.grpc.AgentSkill proto);
 }

spec-grpc/src/main/java/io/a2a/grpc/mapper/HTTPAuthSecuritySchemeMapper.java

@@ -16,4 +16,15 @@ public interface HTTPAuthSecuritySchemeMapper {
     @Mapping(target = "bearerFormat", source = "bearerFormat", conditionExpression = "java(domain.getBearerFormat() != null)")
     @Mapping(target = "description", source = "description", conditionExpression = "java(domain.getDescription() != null)")
     io.a2a.grpc.HTTPAuthSecurityScheme toProto(io.a2a.spec.HTTPAuthSecurityScheme domain);
+
+    default io.a2a.spec.HTTPAuthSecurityScheme fromProto(io.a2a.grpc.HTTPAuthSecurityScheme proto) {
+        if (proto == null) {
+            return null;
+        }
+
+        String bearerFormat = proto.getBearerFormat().isEmpty() ? null : proto.getBearerFormat();
+        String description = proto.getDescription().isEmpty() ? null : proto.getDescription();
+
+        return new io.a2a.spec.HTTPAuthSecurityScheme(bearerFormat, proto.getScheme(), description);
+    }
 }

spec-grpc/src/main/java/io/a2a/grpc/mapper/MutualTLSSecuritySchemeMapper.java

@@ -15,4 +15,14 @@ public interface MutualTLSSecuritySchemeMapper {
 
     @Mapping(target = "description", source = "description", conditionExpression = "java(domain.getDescription() != null)")
     io.a2a.grpc.MutualTlsSecurityScheme toProto(io.a2a.spec.MutualTLSSecurityScheme domain);
+
+    default io.a2a.spec.MutualTLSSecurityScheme fromProto(io.a2a.grpc.MutualTlsSecurityScheme proto) {
+        if (proto == null) {
+            return null;
+        }
+
+        String description = proto.getDescription().isEmpty() ? null : proto.getDescription();
+
+        return new io.a2a.spec.MutualTLSSecurityScheme(description);
+    }
 }

spec-grpc/src/main/java/io/a2a/grpc/mapper/OAuth2SecuritySchemeMapper.java

@@ -17,4 +17,16 @@ public interface OAuth2SecuritySchemeMapper {
     @Mapping(target = "description", source = "description", conditionExpression = "java(domain.getDescription() != null)")
     @Mapping(target = "oauth2MetadataUrl", source = "oauth2MetadataUrl", conditionExpression = "java(domain.getOauth2MetadataUrl() != null)")
     io.a2a.grpc.OAuth2SecurityScheme toProto(io.a2a.spec.OAuth2SecurityScheme domain);
+
+    default io.a2a.spec.OAuth2SecurityScheme fromProto(io.a2a.grpc.OAuth2SecurityScheme proto) {
+        if (proto == null) {
+            return null;
+        }
+
+        io.a2a.spec.OAuthFlows flows = OAuthFlowsMapper.INSTANCE.fromProto(proto.getFlows());
+        String description = proto.getDescription().isEmpty() ? null : proto.getDescription();
+        String oauth2MetadataUrl = proto.getOauth2MetadataUrl().isEmpty() ? null : proto.getOauth2MetadataUrl();
+
+        return new io.a2a.spec.OAuth2SecurityScheme(flows, description, oauth2MetadataUrl);
+    }
 }

spec-grpc/src/main/java/io/a2a/grpc/mapper/OAuthFlowsMapper.java

@@ -19,4 +19,6 @@ public interface OAuthFlowsMapper {
     OAuthFlowsMapper INSTANCE = A2AMappers.getMapper(OAuthFlowsMapper.class);
 
     io.a2a.grpc.OAuthFlows toProto(io.a2a.spec.OAuthFlows domain);
+
+    io.a2a.spec.OAuthFlows fromProto(io.a2a.grpc.OAuthFlows proto);
 }