tweak how DockerFile buildArgs are handled internally, and change out…

…put to match C# output (as a map, not an array)

aspire4j/aspire4j/src/main/java/com/microsoft/aspire/resources/DockerFile.java

@@ -4,6 +4,7 @@
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.annotation.JsonPropertyOrder;
 import com.fasterxml.jackson.databind.annotation.JsonSerialize;
+import com.microsoft.aspire.resources.annotations.KeyValueAnnotation;
 import com.microsoft.aspire.utils.json.RelativePath;
 import com.microsoft.aspire.utils.json.RelativePathSerializer;
 import com.microsoft.aspire.resources.traits.ResourceWithEndpoints;
@@ -64,9 +65,6 @@ public class DockerFile<T extends DockerFile<T>> extends Resource<T>
     @RelativePath
     private String context;
 
-    @JsonProperty("buildArgs")
-    private List<String[]> buildArgs;
-
     public DockerFile(String name) {
         this(name, null, null);
     }
@@ -108,10 +106,7 @@ public T withContext(String context) {
     }
 
     public T withBuildArg(String key, String value) {
-        if (buildArgs == null) {
-            buildArgs = new ArrayList<>();
-        }
-        buildArgs.add(new String[] { key, value });
+        withAnnotation(new KeyValueAnnotation("DockerFile_buildArg", key, value));
         return self();
     }
 

aspire4j/aspire4j/src/main/java/com/microsoft/aspire/resources/annotations/KeyValueAnnotation.java

@@ -0,0 +1,36 @@
+package com.microsoft.aspire.resources.annotations;
+
+import java.util.Objects;
+
+public class KeyValueAnnotation implements ResourceAnnotation {
+    private final String type;
+    private final String key;
+    private final Object value;
+
+    public KeyValueAnnotation(String type, String key, Object value) {
+        this.type = Objects.requireNonNull(type, "Type cannot be null");
+        this.key = Objects.requireNonNull(key, "Key cannot be null");
+        this.value = Objects.requireNonNull(value, "Value cannot be null");
+    }
+
+    public String getType() {
+        return type;
+    }
+
+    public String getKey() {
+        return key;
+    }
+
+    public Object getValue() {
+        return value;
+    }
+
+    @Override
+    public String toString() {
+        return "KeyValueAnnotation{" +
+            "type='" + type + '\'' +
+            ", key='" + key + '\'' +
+            ", value='" + value + '\'' +
+            '}';
+    }
+}

aspire4j/aspire4j/src/main/java/com/microsoft/aspire/utils/json/ResourceSerializer.java

@@ -7,9 +7,11 @@
 import com.fasterxml.jackson.databind.SerializerProvider;
 import com.fasterxml.jackson.databind.ser.BeanSerializerFactory;
 import com.microsoft.aspire.implementation.ResourceUtilities;
+import com.microsoft.aspire.resources.DockerFile;
 import com.microsoft.aspire.resources.Resource;
 import com.microsoft.aspire.resources.annotations.EndpointAnnotation;
 import com.microsoft.aspire.resources.annotations.EnvironmentCallbackAnnotation;
+import com.microsoft.aspire.resources.annotations.KeyValueAnnotation;
 import com.microsoft.aspire.resources.properties.*;
 import com.microsoft.aspire.resources.references.ReferenceExpression;
 import com.microsoft.aspire.resources.traits.ManifestExpressionProvider;
@@ -44,6 +46,10 @@ public void serialize(Resource<?> resource, JsonGenerator gen, SerializerProvide
         writeEnvironmentVariables(resource, gen);
         writeBindings(resource, gen);
 
+        if (resource instanceof DockerFile<?> dockerResource) {
+            writeBuildArgs(dockerResource, gen);
+        }
+
         gen.writeEndObject();
     }
 
@@ -108,6 +114,26 @@ private void writeEnvironmentVariables(Resource<?> resource, JsonGenerator gen)
         }
     }
 
+    private void writeBuildArgs(DockerFile<?> dockerResource, JsonGenerator gen) throws IOException {
+        writeObjectField("buildArgs",
+            collectKeyValueAnnotations(dockerResource, "DockerFile_buildArg"),
+            gen);
+    }
+
+    private Map<String, Object> collectKeyValueAnnotations(Resource<?> resource, String type) {
+        return resource.getAnnotations().stream()
+            .filter(a -> a instanceof KeyValueAnnotation keyValueAnnotation && type.equals(keyValueAnnotation.getType()))
+            .map(a -> (KeyValueAnnotation) a)
+            .collect(Collectors.toMap(KeyValueAnnotation::getKey, KeyValueAnnotation::getValue));
+    }
+
+    private void writeObjectField(String name, Map<?,?> map, JsonGenerator gen) throws IOException {
+        Objects.requireNonNull(map);
+        if (!map.isEmpty()) {
+            gen.writeObjectField(name, map);
+        }
+    }
+
     private void tryAddDependentResources(Object value) {
         if (value instanceof Resource<?> resource) {
             referencedResources.put(resource.getName(), resource);