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.
assertEdgeNotInGraphErrorMessage(e);
    }
  }
  @Test
  public void target_oneEdge() {
    addEdge(N1, N2, E12);
    assertThat(network.incidentNodes(E12).target()).isEqualTo(N2);
  }
  @Test
  public void target_edgeNotInGraph() {
    try {
      network.incidentNodes(EDGE_NOT_IN_GRAPH).target();
      fail(ERROR_EDGE_NOT_IN_GRAPH);
    } catch (IllegalArgumentException e) {
      assertEdgeNotInGraphErrorMessage(e);
    }
  }
  @Test
  public void inDegree_oneEdge() {
    addEdge(N1, N2, E12);
    assertThat(network.inDegree(N2)).isEqualTo(1);
    
    assertThat(network.inDegree(N1)).isEqualTo(0);
  }
  @Test
  public void outDegree_oneEdge() {
    addEdge(N1, N2, E12);
    assertThat(network.outDegree(N1)).isEqualTo(1);
    
    assertThat(network.outDegree(N2)).isEqualTo(0);