Fix missing imports for schemaMapping in API interfaces

Author: SubhamAshok

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

@@ -4623,6 +4623,8 @@ public CodegenOperation fromOperation(String path,
                         !languageSpecificPrimitives.contains(r.baseType)) {
                     imports.add(r.baseType);
                 }
+                
+                addImportMappedType(imports, r.dataType);
 
                 if ("set".equals(r.containerType) && typeMapping.containsKey(r.containerType)) {
                     op.uniqueItems = true;
@@ -4868,6 +4870,17 @@ public CodegenOperation fromOperation(String path,
         return op;
     }
 
+    /**
+     * Helper method to add an import for a data type if it exists in the importMapping.
+     * @param imports The set of imports to add to.
+     * @param dataType The data type to check for a mapping.
+     */
+    protected void addImportMappedType(Set<String> imports, String dataType) {
+        if (importMapping.containsKey(dataType)) {
+            imports.add(dataType);
+        }
+    }
+
     public void SortParametersByRequiredFlag(List<CodegenParameter> parameters) {
         Collections.sort(parameters, new Comparator<CodegenParameter>() {
             @Override
@@ -5464,6 +5477,7 @@ public CodegenParameter fromParameter(Parameter parameter, Set<String> imports)
         if (codegenProperty.complexType != null) {
             imports.add(codegenProperty.complexType);
         }
+        addImportMappedType(imports, codegenParameter.dataType);
 
         codegenParameter.pattern = toRegularExpression(parameterSchema.getPattern());