Guava vendor version conflict when deserializing Task object

1. Description

There are two guava dependencies of Nemo: com.google.guava, org.apache.beam.vendor.guava

The latter was introduced in beam for long. Since Nemo already updated Beam version from 2.6 to 2.11, we have to also include org.apache.beam.vendor.guava in our dependencies. In beam 2.6, we did not have this vendor guava.

During deserialization, Task cannot be deserialized and cast successfully, and we presume it is because of this two guava libraries, that we have the below ClassCastException.

1. Error Message

java.lang.ClassCastException: cannot assign instance of org.apache.beam.vendor.guava.v20_0.com.google.common.collect.ImmutableBiMap$SerializedForm to field org.apache.beam.sdk.transforms.display.DisplayData.entries of type org.apache.beam.vendor.guava.v20_0.com.google.common.collect.ImmutableMap in instance of org.apache.beam.sdk.transforms.display.DisplayData

1. Steps to reproduce

https://github.com/apache/incubator-nemo/pull/237

1. References

Stackoverflow: readresolve-not-working-an-instance-of-guavas-serializedform-appears
Stackoverflow: java serialization error when reloading in new run of a program