Paraphrased from customer email:

In com.sun.net.ssl.internal.ssl.Record.java, maxDataSize is defined as 16384 as per the TLS 1.0 RFC (http://www.rfc.net/rfc2246.html Section 6.2.1). However, our partner's system is not compatible with the RFC, sending us 30KB TLS fragments. This incompatibility causes the following exception:

javax.net.ssl.SSLProtocolException: Input SSL/TLS record too big: max = 16665 len = 27314
            at com.sun.net.ssl.internal.ssl.SSLEngineImpl.readNetRecord(SSLEngineImpl.java:770)
            at com.sun.net.ssl.internal.ssl.SSLEngineImpl.unwrap(SSLEngineImpl.java:674)
            at javax.net.ssl.SSLEngine.unwrap(SSLEngine.java:566)
            at com.facetime.imstack.socket.impl.ssl.SslConnection.socketReadEvent(SslConnection.java:157)
            at com.facetime.imstack.socket.impl.nio.NioConnection.selectedEvent(NioConnection.java:208)
            at com.facetime.imstack.socket.impl.nio.NioDispatcher._processSelected(NioDispatcher.java:148)
            at com.facetime.imstack.socket.impl.nio.NioDispatcher.run(NioDispatcher.java:214)
            at java.lang.Thread.run(Thread.java:595)

While this is not a JDK issue, as the JSSE code is correct according to the RFC, it prevents the JDK from interoperating with these non-compliant stacks. The customer requests that the JDK code support interoperability with these stacks, either by being able to specify the maximum record size via a system property or similar, or by having the code dynamically detect incoming packets that are too large and handling them appropriately.