src/vs/workbench/contrib/debug/browser/debugSession.ts/DebugSession/breakpointsLocations
class DebugSession:	async breakpointsLocations(uri: URI, lineNumber: number): Promise<IPosition[]> {
		if (!this.raw) {
			throw new Error(localize('noDebugAdapter', "No debugger available, can not send '{0}'", 'breakpoints locations'));
		}

		const source = this.getRawSource(uri);
		const response = await this.raw.breakpointLocations({ source, line: lineNumber });
		if (!response || !response.body || !response.body.breakpoints) {
			return [];
		}

		const positions = response.body.breakpoints.map(bp => ({ lineNumber: bp.line, column: bp.column || 1 }));

		return distinct(positions, p => `${p.lineNumber}:${p.column}`);
	}