Member predicate ExportDeclaration :: getImportAssertion
Gets the object literal passed as part of the assert
clause, if this is
a re-export declaration.
For example, this gets the { type: "json" }
expression in each of the following:
export { x } from 'foo' assert { type: "json" };
export * from 'foo' assert { type: "json" };
export * as x from 'foo' assert { type: "json" };