Provide a clearer exception message when building a ReadBatch or WriteBatch without setting the mappedTableResource (table)

[swar8080]

Currently, a NullPointerException is thrown if you forget to call the WriteBatch builder with mappedTableResource(MappedTableResource<T>). ReadBatch has the same problem

Motivation and Context

    DynamoDbEnhancedClient client ...
    DynamoDbTable<Customer> customerTable = client.table("customer-table", customerSchema);
    Customer customer = ...

    // This will fail with a NullPointerException, both for addPutItem* and addDeleteItem*
    client.batchWriteItem(builder -> builder.addWriteBatch(
        WriteBatch.builder(Customer.class)
            .addPutItem(customer)
            .build()
    ));

   // This works correctly
   client.batchWriteItem(builder -> builder.addWriteBatch(
        WriteBatch.builder(Customer.class)
            .mappedTableResource(customerTable)
            .addPutItem(customer)
            .build()
    ));

Modifications

Add a clearer error message in the NullPointerException letting the person know they forgot to set a mappedTableResource

Testing

Updated unit tests

Types of changes

• Bug fix (non-breaking change which fixes an issue)

Checklist

• I have read the CONTRIBUTING document
• Local run of mvn install succeeds
• My code follows the code style of this project
• My change requires a change to the Javadoc documentation
• I have updated the Javadoc documentation accordingly
• I have added tests to cover my changes
• All new and existing tests passed
• I have added a changelog entry. Adding a new entry must be accomplished by running the scripts/new-change script and following the instructions. Commit the new file created by the script in .changes/next-release with your changes.

License

• I confirm that this pull request can be released under the Apache 2 license

[debora-ito]

@swar8080 I understand the problem, but I don't think we should deprecate the current builder for this.
Do you think a better error message in case of a null mappedTableResource would be helpful?

[swar8080]

@debora-ito okay I just updated the NullPointerException's message and got rid of the other changes

[dagnir]

LGTM. Thanks for the contribution!

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

100.0% Coverage
0.0% Duplication

[dagnir]

@all-contributors please add @swar8080 for code

[allcontributors]

@dagnir

I've put up a pull request to add @swar8080! 🎉