ActivityPropertyChangeDetails

Which field of a contact or company changed, and its values before and after.

field
Type: string
required

Name of the field that changed.
new_value
Type: string
required

Value after the change, or an empty string. A company industry, size or source reads as its display label.
old_value
Type: string
required

Value before the change, or an empty string. A company industry, size or source reads as its display label.