fix: add @JsonInclude(NON_NULL) to MarkStepCompletedRequest

Prevents null metrics fields from serializing as explicit "null" values
in JSON. Matches the pattern used by all other request types in the SDK.

Author: saurabhjain1592

CHANGELOG.md

@@ -13,7 +13,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Media governance types: `MediaGovernanceConfig`, `MediaGovernanceStatus`
 - Media policy category constants: `CATEGORY_MEDIA_SAFETY`, `CATEGORY_MEDIA_BIOMETRIC`, `CATEGORY_MEDIA_PII`, `CATEGORY_MEDIA_DOCUMENT`
 - `PolicyCategory` enum values: `MEDIA_SAFETY`, `MEDIA_BIOMETRIC`, `MEDIA_PII`, `MEDIA_DOCUMENT`
-- StepComplete now accepts post-execution metrics (`tokens_in`, `tokens_out`, `cost_usd`)
+- `MarkStepCompletedRequest` now accepts post-execution metrics (`tokens_in`, `tokens_out`, `cost_usd`)
 
 ---
 

src/main/java/com/getaxonflow/sdk/types/workflow/WorkflowTypes.java

@@ -17,6 +17,7 @@
 
 import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
+import com.fasterxml.jackson.annotation.JsonInclude;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.annotation.JsonValue;
 
@@ -845,6 +846,7 @@ public int getTotal() {
      * Request to mark a step as completed.
      */
     @JsonIgnoreProperties(ignoreUnknown = true)
+    @JsonInclude(JsonInclude.Include.NON_NULL)
     public static final class MarkStepCompletedRequest {
 
         @JsonProperty("output")