go: Fix missing imports for optional body params.

Previos mustache template was using #isBodyParam outside of #operations
context, so it was not effective.

Even if we'd add the proper context, we'd then risk generating duplicate
imports for multiple matching parameters.

For this reason, this patch implements detection of an optional body
parameter in code, making sure the corresponding import is added just
once.

Fixes #19237

Author: booxter

modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenOperation.java

@@ -115,6 +115,15 @@ public boolean getHasBodyParam() {
         return nonEmpty(bodyParams);
     }
 
+    /**
+     * Check if there's at least one optional body parameter
+     *
+     * @return true if optional body parameter exists, false otherwise
+     */
+    public boolean getHasOptionalBodyParam() {
+        return nonEmpty(bodyParams) && nonEmpty(optionalParams) && bodyParams.stream().anyMatch(optionalParams::contains);
+    }
+
     /**
      * Check if there's at least one query parameter
      *

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/GoServerCodegen.java

@@ -410,6 +410,7 @@ public OperationsMap postProcessOperationsWithModels(OperationsMap objs, List<Mo
     private void addConditionalImportInformation(OperationsMap operations) {
         boolean hasPathParams = false;
         boolean hasBodyParams = false;
+        boolean hasOptionalBodyParams = false;
 
         for (CodegenOperation op : operations.getOperations().getOperation()) {
             if (op.getHasPathParams()) {
@@ -418,10 +419,14 @@ private void addConditionalImportInformation(OperationsMap operations) {
             if (op.getHasBodyParam()) {
                 hasBodyParams = true;
             }
+            if (op.getHasOptionalBodyParam()) {
+                hasOptionalBodyParams = true;
+            }
         }
 
         additionalProperties.put("hasPathParams", hasPathParams);
         additionalProperties.put("hasBodyParams", hasBodyParams);
+        additionalProperties.put("hasOptionalBodyParams", hasOptionalBodyParams);
     }
 
 

modules/openapi-generator/src/main/resources/go-server/controller-api.mustache

@@ -6,12 +6,10 @@ import (
 	{{#hasBodyParams}}
 	"encoding/json"
 	{{/hasBodyParams}}
-	{{#isBodyParam}}
-	    {{^required}}
+	{{#hasOptionalBodyParams}}
 	"errors"
 	"io"
-	    {{/required}}
-	{{/isBodyParam}}
+	{{/hasOptionalBodyParams}}
 	"net/http"
 	"strings"
 {{#imports}}	"{{import}}"