Returns the schema a report type produces - the ordered columns that appear in its output. For report types with fixed columns, these are the report type's preview columns. For configurable report types, they are the client-named columns defined by the report type's column mapping parameters. Report types whose columns depend on the client's own configuration resolve them against the report type's declared parameter defaults, which the response echoes as context_parameters. To resolve the columns against your own parameter values instead, post them to this same path. Use this to discover a report type's output shape without running the report.