@Beta
    public ScanSpec withExpressionSpec(ScanExpressionSpec xspec) {
        return withFilterExpression(xspec.getFilterExpression())
              .withProjectionExpression(xspec.getProjectionExpression())
              .withNameMap(xspec.getNameMap())
              .withValueMap(xspec.getValueMap())
              ;
    }
Convenient method to specify expressions (and the associated name map and
value map) via {@link ScanExpressionSpec}.
aws-java-sdk-dynamodb/src/main/java/com/amazonaws/services/dynamodbv2/document/spec/ScanSpec.java