Provide description on DataSourceMessageBuilder

Description

When set enableStreaming to true in file connector configuration it gives following error

<file.read configKey="FILE_LOCAL">
                <path>home/sample.xml</path>
                <readMode>Complete File</readMode>
                <contentType>application/binary</contentType>
                <includeResultTo>Message Property</includeResultTo>
                <resultPropertyName>resultproperty</resultPropertyName>
                <enableStreaming>true</enableStreaming>
                <enableLock>false</enableLock>
            </file.read>

[2024-08-14 12:38:11,268] ERROR {ReadFile} - {proxy:sample} Error while performing file:read for file/directory file:////Users/sajithmadhusanka/Documents/CS/TICKETS/DRGSUB-158/source/file.xml org.wso2.carbon.connector.exception.FileOperationException: Required builder for streaming not found
    at org.wso2.carbon.connector.operations.ReadFile.setStreamToSynapse(ReadFile.java:601)
    at org.wso2.carbon.connector.operations.ReadFile.readFileContent(ReadFile.java:369)
    at org.wso2.carbon.connector.operations.ReadFile.connect(ReadFile.java:172)
    at org.wso2.carbon.connector.core.AbstractConnector.mediate(AbstractConnector.java:32)
    at org.apache.synapse.mediators.ext.ClassMediator.updateInstancePropertiesAndMediate(ClassMediator.java:178)
    at org.apache.synapse.mediators.ext.ClassMediator.mediate(ClassMediator.java:97)
    at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:110)
    at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:72)
    at org.apache.synapse.mediators.template.TemplateMediator.mediate(TemplateMediator.java:136)
    at org.apache.synapse.mediators.template.InvokeMediator.mediate(InvokeMediator.java:170)
    at org.apache.synapse.mediators.template.InvokeMediator.mediate(InvokeMediator.java:93)
    at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:110)
    at org.apache.synapse.mediators.AbstractListMediator.mediate(AbstractListMediator.java:72)
    at org.apache.synapse.mediators.base.SequenceMediator.mediate(SequenceMediator.java:158)
    at org.apache.synapse.core.axis2.ProxyServiceMessageReceiver.receive(ProxyServiceMessageReceiver.java:228)
    at org.apache.axis2.engine.AxisEngine.receive(AxisEngine.java:180)
    at org.apache.synapse.transport.passthru.ServerWorker.processNonEntityEnclosingRESTHandler(ServerWorker.java:396)
    at org.apache.synapse.transport.passthru.ServerWorker.run(ServerWorker.java:210)
    at org.apache.axis2.transport.base.threads.NativeWorkerPool$1.run(NativeWorkerPool.java:172)
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
    at java.base/java.lang.Thread.run(Thread.java:829)

According to the source code [1] the builder is not a type of DataSourceMessageBuilder, which is why the above error is thrown.

We haven't classified which message builders are DataSourceMessageBuilders. Therefore, it would be better if we could update the MI documentation [2] with these classifications. As this issue can occur when setting up file connector, it is better to add a note in file connector docs too.

[1] https://github.com/wso2-extensions/esb-connector-file/blob/a5a7293080dccb864443f80334728ddb2861c694/src/main/java/org/wso2/carbon/connector/operations/ReadFile.java#L590 [2] https://mi.docs.wso2.com/en/latest/install-and-setup/setup/message-builders-formatters/message-builders-and-formatters/

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wso2 / docs-mi