You are an expert AI system. Your ONLY job is to return a single, valid JSON object that strictly follows the schema provided.

---
**ABSOLUTE RULES FOR JSON OUTPUT:**
1.  The final output MUST be a single JSON object and nothing else.
2.  The root object MUST have exactly two keys: "events" and "stateful_relationships".
3.  If no events are found, the value for "events" MUST be an empty list: `[]`.
4.  If no stateful relationships are found, the value for "stateful_relationships" MUST be an empty list: `[]`.
5.  Every object inside the "events", "participants", and "stateful_relationships" lists MUST contain ALL required keys from the schema. DO NOT OMIT ANY KEYS.
6.  Do NOT add any extra keys that are not defined in the schema. Do not add explanations in the JSON.
---

### SCHEMA DEFINITION
... (The schema definition section remains the same as last time) ...
---
EXAMPLE 1 (Complex Case)
Text: "On January 15, 2022, a press release announced that Sarah Chen was appointed CEO of a company called OmniCorp. She officially left her position on May 1, 2024."
Document Timestamp: "2024-05-02"

JSON Output:
{
  "events": [
    {
      "event_type": "APPOINTMENT",
      "event_description": "Sarah Chen was appointed CEO of OmniCorp.",
      "timestamp": "2022-01-15",
      "source_text": "On January 15, 2022, a press release announced that Sarah Chen was appointed CEO of a company called OmniCorp.",
      "participants": [
        {"entity_name": "Sarah Chen", "entity_type": "Person", "role": "appointee"},
        {"entity_name": "OmniCorp", "entity_type": "Company", "role": "employer"}
      ]
    },
    {
      "event_type": "RESIGNATION",
      "event_description": "Sarah Chen left her position as CEO of OmniCorp.",
      "timestamp": "2024-05-01",
      "source_text": "Sarah Chen officially left her position on May 1, 2024.",
       "participants": [
        {"entity_name": "Sarah Chen", "entity_type": "Person", "role": "resignee"},
        {"entity_name": "OmniCorp", "entity_type": "Company", "role": "former_employer"}
      ]
    }
  ],
  "stateful_relationships": [
    {
      "source_entity_name": "Sarah Chen",
      "source_entity_type": "Person",
      "relationship_type": "CEO_OF",
      "target_entity_name": "OmniCorp",
      "target_entity_type": "Company",
      "start_time": "2022-01-15",
      "end_time": "2024-05-01",
      "source_text": "Sarah Chen was appointed CEO of a company called OmniCorp. She officially left her position on May 1, 2024."
    }
  ]
}
---
EXAMPLE 2 (Simple Case with No Stateful Relationship)
Text: "Innovate Bank reported a security breach on its main server on July 4, 2024."
Document Timestamp: "2024-07-05"

JSON Output:
{
  "events": [
    {
      "event_type": "SECURITY_BREACH",
      "event_description": "Innovate Bank reported a security breach on its main server.",
      "timestamp": "2024-07-04",
      "source_text": "Innovate Bank reported a security breach on its main server on July 4, 2024.",
      "participants": [
          { "entity_name": "Innovate Bank", "entity_type": "Company", "role": "victim" }
      ]
    }
  ],
  "stateful_relationships": []
}
---

Now, strictly follow all rules and the schema to extract information from the following text.

Text: "
    New York, NY - March 1, 2021 - Following a board meeting, tech conglomerate 'Stellar Dynamics'
    announced that Maria Flores has been appointed as the new Chief Executive Officer, effective immediately.
    "
Document Timestamp: "2021-03-01T09:00:00Z"