fix(openapiv2): Invalid entries in body parameter schema required array when using body: "field_name" (#6088)

* fix(openapiv2): remove invalid body field name from schema required array

When generating OpenAPI schemas for body parameters with body: "field_name"
and path parameters extracted from nested fields, the body field name was
incorrectly added to the schema's required array via updateSwaggerObjectFromFieldBehavior.

For example, with UpdateCommentRequest containing a required Comment field,
and Comment having a required "comment" field, when using path parameter
{comment.name} and body: "comment", the generated body schema incorrectly had:
  required: ["comment", "resource", "author", "comment"]
Or when the field name doesn't exist as a property:
  required: ["title", "direction"] where "direction" is not a property

This fix filters the required array after calling renderFieldAsDefinition to:
1. Remove duplicate entries of the body field name
2. Remove the body field name if it's not actually a property of the schema
The body parameter's required status is already correctly set via the
parameter's required: true attribute.

* chore(openapiv2): regenerate examples with body parameter required fix

The fix in template.go correctly removes invalid body field names from the
required array when they are not properties of the schema. This regeneration
updates a_bit_of_everything.swagger.json to remove the incorrectly included
'book' field from the required array in the UpdateBookRequest body parameter.

Related to body parameter schema generation fix.

Author: rdark

examples/internal/proto/examplepb/a_bit_of_everything.swagger.json

@@ -5071,10 +5071,7 @@
                 }
               },
               "description": "The book's `name` field is used to identify the book to be updated.\nFormat: publishers/{publisher}/books/{book}",
-              "title": "The book to update.",
-              "required": [
-                "book"
-              ]
+              "title": "The book to update."
             }
           },
           {

protoc-gen-openapiv2/internal/genopenapi/template.go

@@ -1565,6 +1565,39 @@ func renderServices(services []*descriptor.Service, paths *openapiPathsObject, r
 							if err != nil {
 								return err
 							}
+							// renderFieldAsDefinition may add the body field name to the schema's required array
+							// via updateSwaggerObjectFromFieldBehavior. However, for body parameters, the schema
+							// represents the field's type, not the containing message. The body field name should
+							// only be in the schema's required array if it's actually a property of the schema.
+							// Remove the body field name from required if it's not a property to avoid invalid entries.
+							if schema.Required != nil && schema.Properties != nil {
+								// Build a set of property names
+								propertyNames := make(map[string]bool)
+								for _, prop := range *schema.Properties {
+									propertyNames[prop.Key] = true
+								}
+								// Filter required array: keep field names that are either:
+								// 1. Not the body field name, OR
+								// 2. The body field name AND it's actually a property
+								filteredRequired := make([]string, 0, len(schema.Required))
+								seenBodyFieldName := false
+								for _, req := range schema.Required {
+									if req == bodyFieldName {
+										if propertyNames[req] {
+											// It's a property, keep it (but only once)
+											if !seenBodyFieldName {
+												filteredRequired = append(filteredRequired, req)
+												seenBodyFieldName = true
+											}
+										}
+										// else: It's not a property, skip it
+									} else {
+										// Not the body field name, keep it
+										filteredRequired = append(filteredRequired, req)
+									}
+								}
+								schema.Required = filteredRequired
+							}
 						}
 						if schema.Title != "" {
 							desc = mergeDescription(schema)