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.
} catch (IllegalArgumentException e) {
      assertThat(e.getMessage()).contains(ERROR_REUSE_EDGE);
    }
    try {
      networkAsMutableNetwork.addEdge(N2, N2, E11);
      fail("Reusing an existing self-loop edge to make a different self-loop edge succeeded");
    } catch (IllegalArgumentException e) {
      assertThat(e.getMessage()).contains(ERROR_REUSE_EDGE);
    }
    addEdge(N1, N2, E12);
    try {
      networkAsMutableNetwork.addEdge(N1, N1, E12);
      fail("Reusing an existing edge to add a self-loop edge between different nodes succeeded");
    } catch (IllegalArgumentException e) {
      assertThat(e.getMessage()).contains(ERROR_REUSE_EDGE);
    }
  }
  @Test
  public void addEdge_parallelSelfLoopEdge_notAllowed() {
    assume().that(graphIsMutable()).isTrue();
    assume().that(network.allowsSelfLoops()).isTrue();
    assume().that(network.allowsParallelEdges()).isFalse();
    addEdge(N1, N1, E11);
    try {
      networkAsMutableNetwork.addEdge(N1, N1, EDGE_NOT_IN_GRAPH);
      fail("Adding a parallel self-loop edge succeeded");
    } catch (IllegalArgumentException e) {
      assertThat(e.getMessage()).contains(ERROR_PARALLEL_EDGE);
    }
  }