1862655 - NullPointerExceptions during IDoc_AEE Receiver Adapter processing

Outbound message processing fails in the IDoc_AAE Receiver Adapter with the errors below from message audit log:

IDoc: Adding control record to payload failed due to Error during
transform: java.lang.NullPointerException: while trying to invoke the
method java.lang.String.length() of an object loaded from local
variable chars
MP: exception caught with message Error during transform:
java.lang.NullPointerException: while trying to invoke the method
java.lang.String.length() of an object loaded from local
variable 'chars'

and from traces (1514898 - Troubleshooting SAP Process Orchestration / Integration):

Message contained wrong value in IDOCTYP-<IDoc Type name>. The value is now set
to null.
Message contained value in CIMTYP-<CIM Type name>. The value is now empty.
Message contained wrong value in MESTYP-<Message Type name>. The value is now set to
null.
ERROR:  'while trying to invoke the method java.lang.String.length() of
an object loaded from local variable 'chars''
[EXCEPTION]
javax.xml.transform.TransformerException:
java.lang.NullPointerException: while trying to invoke the method
java.lang.String.length() of an object loaded from local variable
'chars'

• SAP NetWeaver 7.3
• SAP enhancement package 1 for SAP NetWeaver 7.3
• SAP NetWeaver 7.4
• SAP NetWeaver 7.5

IDOC_ERROR_PARSE_FAILURE, IDoc Extension, MSGTYP, IDOCTYP, CIMTYP, urn:sap-com:document:sap:idoc:messages, Process Integration 7.30, PI 7.30, Process Integration 7.31, PI 7.31, Process Orchestration 7.4, PI 7.4, PO 7.4, Process Orchestration 7.5, PI 7.5, PO 7.5, XI, AEX , KBA , BC-XI-CON-IDO , Idoc Adapter J2EE , Problem