diff --git a/core/src/lib.rs b/core/src/lib.rs
index 4306fc7..f66791a 100644
--- a/core/src/lib.rs
+++ b/core/src/lib.rs
@@ -373,4 +373,74 @@ mod unit_tests {
         assert!(script.environment.is_some());
         assert_eq!(script.environment.as_ref().unwrap().get("FOO"), Some(&"bar".to_string()));
     }
+
+    #[test]
+    fn test_extension_definition_serialization() {
+        let extension_json = json!({
+            "document": {
+                "dsl": "1.0.2",
+                "namespace": "test",
+                "name": "sample-workflow",
+                "version": "0.1.0"
+            },
+            "use": {
+                "extensions": [
+                    {
+                    "mockService": {
+                        "extend": "call",
+                        "when": "($task.with.endpoint != null and ($task.with.endpoint | startswith(\"https://mocked.service.com\"))) or ($task.with.endpoint.uri != null and ($task.with.endpoint.uri | startswith(\"https://mocked.service.com\")))",
+                        "before": [
+                            {
+                                "mockResponse": {
+                                    "set": {
+                                        "statusCode": 200,
+                                        "headers": {
+                                            "Content-Type": "application/json"
+                                        },
+                                        "content": {
+                                            "foo": {
+                                                "bar": "baz"
+                                            }
+                                        }
+                                    },
+                                    "then": "exit"
+                                }
+                            }
+                        ]
+                    }
+                }
+                ]
+            },
+            "do": [
+                {
+                    "callHttp": {
+                        "call": "http",
+                        "with": {
+                            "method": "get",
+                            "endpoint": {
+                                "uri": "https://fake.com/sample"
+                            }
+                        }
+                    }
+                }
+            ]
+        });
+        let result: Result<WorkflowDefinition, _> = serde_json::from_value(extension_json);
+        match result {
+            Ok(workflow) => {
+                // Verify the workflow was deserialized correctly
+                assert_eq!(workflow.document.namespace, "test");
+                assert_eq!(workflow.document.name, "sample-workflow");
+                assert_eq!(workflow.document.version, "0.1.0");
+                // Verify the use section exists with extensions
+                assert!(workflow.use_.is_some());
+                if let Some(use_def) = workflow.use_ {
+                    assert!(use_def.extensions.is_some());
+                }
+            }
+            Err(e) => {
+                panic!("Failed to deserialize workflow with extension: {}", e);
+            }
+        }
+    }
 }
\ No newline at end of file
diff --git a/core/src/models/extension.rs b/core/src/models/extension.rs
index 241e3f9..5f80ed9 100644
--- a/core/src/models/extension.rs
+++ b/core/src/models/extension.rs
@@ -14,12 +14,11 @@ pub struct ExtensionDefinition{
     #[serde(rename = "when", skip_serializing_if = "Option::is_none")]
     pub when: Option<String>,
 
-    /// Gets/sets a name/definition map, if any, of the tasks to execute before the extended task
+    /// Gets/sets a name/definition list, if any, of the tasks to execute before the extended task
     #[serde(rename = "before", skip_serializing_if = "Option::is_none")]
-    pub before: Option<HashMap<String, TaskDefinition>>,
+    pub before: Option<Vec<HashMap<String, TaskDefinition>>>,
 
-    /// Gets/sets a name/definition map, if any, of the tasks to execute after the extended task
+    /// Gets/sets a name/definition list, if any, of the tasks to execute after the extended task
     #[serde(rename = "after", skip_serializing_if = "Option::is_none")]
-    pub after: Option<HashMap<String, TaskDefinition>>
-
+    pub after: Option<Vec<HashMap<String, TaskDefinition>>>
 }
\ No newline at end of file
diff --git a/core/src/models/task.rs b/core/src/models/task.rs
index 49e9dc9..c80dc4a 100644
--- a/core/src/models/task.rs
+++ b/core/src/models/task.rs
@@ -715,16 +715,25 @@ pub struct ContainerProcessDefinition{
     #[serde(rename = "environment", skip_serializing_if = "Option::is_none")]
     pub environment: Option<HashMap<String, String>>,
 
+    /// Gets/sets the data to pass to the process via stdin, if any
+    #[serde(rename = "stdin", skip_serializing_if = "Option::is_none")]
+    pub stdin: Option<String>,
+
+    /// Gets/sets a list of arguments, if any, to pass to the container (argv)
+    #[serde(rename = "arguments", skip_serializing_if = "Option::is_none")]
+    pub arguments: Option<Vec<String>>,
 }
 impl ContainerProcessDefinition {
-    pub fn new(image: &str, name: Option<String>, command: Option<String>, ports: Option<HashMap<u16, u16>>, volumes: Option<HashMap<String, String>>, environment: Option<HashMap<String, String>>) -> Self{
+    pub fn new(image: &str, name: Option<String>, command: Option<String>, ports: Option<HashMap<u16, u16>>, volumes: Option<HashMap<String, String>>, environment: Option<HashMap<String, String>>, stdin: Option<String>, arguments: Option<Vec<String>>) -> Self{
         Self { 
             image: image.to_string(), 
             name,
             command, 
             ports, 
             volumes, 
-            environment
+            environment,
+            stdin,
+            arguments,
         }
     }
 }
diff --git a/core/src/models/workflow.rs b/core/src/models/workflow.rs
index 8493c7e..6cfe0ce 100644
--- a/core/src/models/workflow.rs
+++ b/core/src/models/workflow.rs
@@ -205,9 +205,9 @@ pub struct ComponentDefinitionCollection{
     #[serde(rename = "errors", skip_serializing_if = "Option::is_none")]
     pub errors: Option<HashMap<String, ErrorDefinition>>,
 
-    /// Gets/sets a name/value mapping of the workflow's extensions, if any
+    /// Gets/sets a list containing the workflow's extensions, if any
     #[serde(rename = "extensions", skip_serializing_if = "Option::is_none")]
-    pub extensions: Option<HashMap<String, ExtensionDefinition>>,
+    pub extensions: Option<Vec<HashMap<String, ExtensionDefinition>>>,
 
     /// Gets/sets a name/value mapping of the workflow's reusable functions
     #[serde(rename = "functions", skip_serializing_if = "Option::is_none")]