BeamSqlExample.java fails to build when running ./gradlew command

In the `BeamSqlExample.java` class, the instructions state that to run the example, use: 

`./gradlew :sdks:java:extensions:sql:runBasicExample`. 

I tried this and the build failed due to `java.lang.IllegalStateException: Unable to return a default Coder`

I will try to fix this!