During some minimization efforts on the previous released version 28.2-jre, I noticed a spurious file in the published version on maven central:

```
tn@proteus:~/Downloads$ unzip -l guava-28.2-jre.jar  | grep swp
    16384  2019-09-18 17:29   com/google/common/collect/.ImmutableListMultimap.java.swp
```

Looks like an transient artefact from an editor that slipped into the release. It is not present in the android variant or in older releases (I checked at least 28.1-jre).

Minor things that can not be changed anymore but maybe a trigger for improvement of future releases.

Edit: I noticed that 29.0 has been released that does not contain this spurious file.
* limitations under the License.
 */
package com.google.common.graph;
import static com.google.common.graph.GraphConstants.ENDPOINTS_MISMATCH;
import static com.google.common.graph.TestUtil.assertEdgeNotInGraphErrorMessage;
import static com.google.common.truth.Truth.assertThat;
import static com.google.common.truth.TruthJUnit.assume;
import static org.junit.Assert.assertTrue;
import static org.junit.Assert.fail;
import com.google.common.collect.ImmutableSet;
import java.util.Collections;
import java.util.Optional;
import java.util.Set;
import org.junit.After;
import org.junit.Test;
/**
 * Abstract base class for testing directed {@link Network} implementations defined in this package.
 */
public abstract class AbstractStandardDirectedNetworkTest extends AbstractNetworkTest {
  @After
  public void validateSourceAndTarget() {
    for (Integer node : network.nodes()) {
      for (String inEdge : network.inEdges(node)) {
        EndpointPair<Integer> endpointPair = network.incidentNodes(inEdge);
        assertThat(endpointPair.source()).isEqualTo(endpointPair.adjacentNode(node));
        assertThat(endpointPair.target()).isEqualTo(node);
      }
      for (String outEdge : network.outEdges(node)) {
        EndpointPair<Integer> endpointPair = network.incidentNodes(outEdge);
        assertThat(endpointPair.source()).isEqualTo(node);