A block with type HEADING_1. Used for large headings.
Unique identifier for this block.
HEADING_1 Groups related blocks together. For standalone blocks, use the block's own uuid. For child blocks (e.g., dropdown options, multiple choice options), use the parent block's uuid so all children share the same groupUuid.
HEADING_1 Payload for HEADING_1 block type. Used for H1 headings.