Including Multiple Attachments In Transaction Kills Node - corda

Question

Setup
Corda 4.6
Working from Java template
I have been experimenting adding up to 10 Attachments of small (1K) zip files to a transaction.
Error when testing with StartedMockNodes:
io.github.classgraph.ClassGraphException: Uncaught exception during scan
at io.github.classgraph.ClassGraphException.newClassGraphException(ClassGraphException.java:89) ~[classgraph-4.8.90.jar:4.8.90]
at io.github.classgraph.ClassGraph.scan(ClassGraph.java:1555) ~[classgraph-4.8.90.jar:4.8.90]
...
Caused by: java.lang.OutOfMemoryError: Java heap space
at nonapi.io.github.classgraph.fastzipfilereader.NestedJarHandler.readAllBytesWithSpilloverToDisk(NestedJarHandler.java:815) ~[classgraph-4.8.90.jar:4.8.90]
at nonapi.io.github.classgraph.fastzipfilereader.PhysicalZipFile.<init>(PhysicalZipFile.java:161) ~[classgraph-4.8.90.jar:4.8.90]
at nonapi.io.github.classgraph.fastzipfilereader.NestedJarHandler.downloadJarFromURL(NestedJarHandler.java:576) ~[classgraph-4.8.90.jar:4.8.90]
...
Error when testing local nodes built with CordForm and connecting with RPC:
Node will stop suddenly. No errors in the log. In the directory of the failed node there will be two files:
hs_err_pid20400.log
java_pid20400.hprof
log file has similar errors as StartedMockNode failures:
j nonapi.io.github.classgraph.fastzipfilereader.NestedJarHandler.readAllBytesWithSpilloverToDisk(Ljava/io/InputStream;Ljava/lang/String;JLnonapi/io/github/classgraph/utils/LogNode;)Lnonapi/io/github/classgraph/fileslice/Slice;+65
j nonapi.io.github.classgraph.fastzipfilereader.PhysicalZipFile.<init>(Ljava/io/InputStream;JLjava/lang/String;Lnonapi/io/github/classgraph/fastzipfilereader/NestedJarHandler;Lnonapi/io/github/classgraph/utils/LogNode;)V+25
j nonapi.io.github.classgraph.fastzipfilereader.NestedJarHandler.downloadJarFromURL(Ljava/lang/String;Lnonapi/io/github/classgraph/utils/LogNode;)Lnonapi/io/github/classgraph/fastzipfilereader/PhysicalZipFile;+428
j nonapi.io.github.classgraph.fastzipfilereader.NestedJarHandler.access$000(Lnonapi/io/github/classgraph/fastzipfilereader/NestedJarHandler;Ljava/lang/String;Lnonapi/io/github/classgraph/utils/LogNode;)Lnonapi/io/github/classgraph/fastzipfilereader/PhysicalZipFile;+3
j nonapi.io.github.classgraph.fastzipfilereader.NestedJarHandler$4.newInstance(Ljava/lang/String;Lnonapi/io/github/classgraph/utils/LogNode;)Ljava/util/Map$Entry;+124
Clarification #1: The error occurs during transaction execution. Not when originally uploading the files to the node using CordaRPCOps.uploadAttachmentWithMetadata (that works fine).
Clarification #2: The first node to fail is the one constructing the transaction. If you try restarting this node it will fail on restart. It will take several re-starts to get up and running again. Then any node that was receiving the transaction will fail. They will also require several restarts to get up an running again. As a testament to Corda's Flow framework - after enough restarts the transaction will eventually be successful and the Attachment's will be transmitted.
Clarification #3: I can pre-upload the Attachments to all the nodes before executing the transaction and the failures still occur.

Answer 1

StartedMockNodes:
Found this
Added the following to my workFlows build.gradle file to stop the errors:
test {
maxHeapSize = "4096m"
}
Local Nodes & RPC:
??? - haven't found a solution yet