Tolerate NULL fields in avro schema

org.apache.beam.sdk.Pipeline$PipelineExecutionException: java.lang.IllegalArgumentException: No enum constant org.talend.sdk.component.api.record.Schema.Type.NULL
 at org.apache.beam.runners.spark.SparkPipelineResult.beamExceptionFrom(SparkPipelineResult.java:66)
 at org.apache.beam.runners.spark.SparkPipelineResult.waitUntilFinish(SparkPipelineResult.java:99)
 at org.apache.beam.runners.spark.SparkPipelineResult.waitUntilFinish(SparkPipelineResult.java:87)
 at org.talend.datastreams.beam.compiler.BeamJob.fullRun(BeamJob.java:269)
 at org.talend.datastreams.beam.compiler.BeamJob.fullRun(BeamJob.java:295)
 at org.talend.datastreams.streamsjob.FullRunJob$.runJob(FullRunJob.scala:89)
 at org.talend.datastreams.streamsjob.FullRunJob$.main(FullRunJob.scala:63)
 at org.talend.datastreams.streamsjob.FullRunJob.main(FullRunJob.scala)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
 at java.lang.reflect.Method.invoke(Method.java:498)
 at org.apache.spark.deploy.SparkSubmit$.org$apache$spark$deploy$SparkSubmit$$runMain(SparkSubmit.scala:775)
 at org.apache.spark.deploy.SparkSubmit$$anon$1.run(SparkSubmit.scala:162)
 at org.apache.spark.deploy.SparkSubmit$$anon$1.run(SparkSubmit.scala:160)
 at java.security.AccessController.doPrivileged(Native Method)
 at javax.security.auth.Subject.doAs(Subject.java:422)
 at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1698)
 at org.apache.spark.deploy.SparkSubmit$.doRunMain$1(SparkSubmit.scala:160)
 at org.apache.spark.deploy.SparkSubmit$.submit(SparkSubmit.scala:205)
 at org.apache.spark.deploy.SparkSubmit$.main(SparkSubmit.scala:119)
 at org.apache.spark.deploy.SparkSubmit.main(SparkSubmit.scala)
 Caused by: java.lang.IllegalArgumentException: No enum constant org.talend.sdk.component.api.record.Schema.Type.NULL
 at java.lang.Enum.valueOf(Enum.java:238)
 at org.talend.sdk.component.api.record.Schema$Type.valueOf(Schema.java:37)
 at org.talend.sdk.component.runtime.beam.spi.record.AvroSchema.doMapType(AvroSchema.java:109)
 at org.talend.sdk.component.runtime.beam.spi.record.AvroSchema.mapType(AvroSchema.java:98)
 at org.talend.sdk.component.runtime.beam.spi.record.AvroSchema.lambda$getEntries$0(AvroSchema.java:75)
 at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193)
 at java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1374)
 at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
 at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)
 at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708)
 at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
 at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:499)
 at org.talend.sdk.component.runtime.beam.spi.record.AvroSchema.getEntries(AvroSchema.java:81)
 at org.talend.sdk.component.runtime.beam.spi.record.AvroSchema.toString(AvroSchema.java:32)
 at org.talend.components.salesforce.service.SalesforceOutputService.createSObject(SalesforceOutputService.java:150)
 at org.talend.components.salesforce.service.SalesforceOutputService.doInsert(SalesforceOutputService.java:305)
 at org.talend.components.salesforce.service.SalesforceOutputService.finish(SalesforceOutputService.java:486)
 at org.talend.components.salesforce.output.SalesforceOutput.release(SalesforceOutput.java:95)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
 at java.lang.reflect.Method.invoke(Method.java:498)
 at org.talend.sdk.component.runtime.base.LifecycleImpl.doInvoke(LifecycleImpl.java:65)
 at org.talend.sdk.component.runtime.base.LifecycleImpl.lambda$invoke$0(LifecycleImpl.java:57)
 at java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:184)
 at java.util.stream.ReferencePipeline$11$1.accept(ReferencePipeline.java:373)
 at java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:175)
 at java.util.Spliterators$ArraySpliterator.forEachRemaining(Spliterators.java:948)
 at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
 at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)
 at java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:151)
 at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:174)
 at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
 at java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:418)
 at org.talend.sdk.component.runtime.base.LifecycleImpl.invoke(LifecycleImpl.java:57)
 at org.talend.sdk.component.runtime.base.LifecycleImpl.stop(LifecycleImpl.java:53)
 at org.talend.sdk.component.runtime.beam.BaseProcessorFn.tearDown(BaseProcessorFn.java:127)