FULL PRODUCT VERSION :
Using today's openjdk-7-ea-src-b12-06_may_2007.zip together with jdk-7-ea-plug-b12-windows-i586-06_may_2007.jar

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows [Version 5.2.3790]

A DESCRIPTION OF THE PROBLEM :
When running "make sanity", the error message states that t2k.lib is missing from the binary plugs. This is true; the binary plugs include t2k.dll, .pdb, and .map, but no .lib. On account of this, you can't build today's OpenJDK on Windows.

ERROR: Can't locate t2k import library.
       Please check your access to
           /c/devtools/jdk-7-binary-plugs/jre/bin/t2k.lib
       and/or check your value of ALT_CLOSED_LIB_DIR.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
On Windows, download openjdk-7-ea-src-b12-06_may_2007.zip and unzip it. Download jdk-7-ea-plug-b12-windows-i586-06_may_2007.jar and run it. Use JDK 1.6.0_00 as your ALT_BOOTDIR and the extracted binary plugs as your ALT_CLOSED_JDK_IMPORT_PATH. cd to control/make and run "make sanity".

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
"make sanity" should not show errors or warnings if configured correctly.
ACTUAL -

ERROR: Can't locate t2k import library.
       Please check your access to
           /c/devtools/jdk-7-binary-plugs/jre/bin/t2k.lib
       and/or check your value of ALT_CLOSED_LIB_DIR.

In that directory, I found t2k.dll, t2k.map and t2k.pdb, but no t2k.lib

ERROR MESSAGES/STACK TRACES THAT OCCUR :

ERROR: Can't locate t2k import library.
       Please check your access to
           /c/devtools/jdk-7-binary-plugs/jre/bin/t2k.lib
       and/or check your value of ALT_CLOSED_LIB_DIR.

REPRODUCIBILITY :
This bug can be reproduced always.

CUSTOMER SUBMITTED WORKAROUND :
Dmitri suggested accepting the JRL, downloading the JRL Java 7 source, and building a t2k.lib from that, which might work.