param.From.String():            from,
				param.SystemNamespace.String(): systemNS,
			}))
		}
	}

	return out
}

// BuildFromAndTo builds only those sources that require both the "From" and "To" parameters.
func (b *Builder) BuildFromAndTo(fromAll echo.Callers, toAll echo.Services) *Builder {
	b.t.Helper()
	out := b.Copy()

	systemNS := istio.ClaimSystemNamespaceOrFail(out.t, out.t)

		// Run setup functions for the callers.
		t.setup(ctx, from.Callers())

		t.toEachDeployment(ctx, func(ctx framework.TestContext, to echo.Instances) {
			// Build and apply per-destination config
			t.cfg.Context(ctx).BuildFromAndTo(firstCaller, to.Services()).Apply()

			t.setupPair(ctx, callers, echo.Services{to})
			t.fromEachWorkloadCluster(ctx, from, func(ctx framework.TestContext, from echo.Instance) {