Additional debug logging for unknown records in HSLF

Recently, while debugging app behavior on HSLF documents, I had to dig into the OOXML that Microsoft PowerPoint places into files saved in PPT format. Having information in the logs about when records were not parsed by POI was very helpful. The hex identifier was critical in being able to quickly search the [MS-PPT] spec for what type of record it was, and the integer identifier was helpful in quickly finding the Record type in RecordTypes.java.

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1887393 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/src/scratchpad/src/org/apache/poi/hslf/record/Record.java b/src/scratchpad/src/org/apache/poi/hslf/record/Record.java
index 2b06b4d..be3bde7 100644
--- a/src/scratchpad/src/org/apache/poi/hslf/record/Record.java
+++ b/src/scratchpad/src/org/apache/poi/hslf/record/Record.java
@@ -25,6 +25,7 @@
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
+import org.apache.logging.log4j.message.StringFormattedMessage;
 import org.apache.poi.common.usermodel.GenericRecord;
 import org.apache.poi.hslf.exceptions.CorruptPowerPointFileException;
 import org.apache.poi.hslf.exceptions.HSLFException;
@@ -169,13 +170,17 @@
 		// A spot of reflection gets us the (byte[],int,int) constructor
 		// From there, we instanciate the class
 		// Any special record handling occurs once we have the class
-		RecordConstructor c = RecordTypes.forTypeID((short)type).recordConstructor;
+		RecordTypes recordType = RecordTypes.forTypeID((short) type);
+		RecordConstructor c = recordType.recordConstructor;
 		if (c == null) {
 			// How odd. RecordTypes normally substitutes in
 			//  a default handler class if it has heard of the record
 			//  type but there's no support for it. Explicitly request
 			//  that now
+			LOG.atDebug().log(() -> new StringFormattedMessage("Known but unhandled record type %d (0x%04x) at offset %d", type, type, start));
 			c = RecordTypes.UnknownRecordPlaceholder.recordConstructor;
+		} else if (recordType == RecordTypes.UnknownRecordPlaceholder) {
+			LOG.atDebug().log(() -> new StringFormattedMessage("Unknown placeholder type %d (0x%04x) at offset %d", type, type, start));
 		}
 
 		final Record toReturn;