incremental builds in the new JDK9 modular build

[Phil Race]

I understood we now build individual modules so when
I touched one java source file in the desktop module I expected to see only
that one module rebuilt but I see this :-

Compiling 2787 files for java.desktop
Note: Some input files use or override a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
Compiling 63 files for jdk.jconsole
Compiling 24 files for java.activation
Compiling 1478 files for java.corba
Compiling 41 files for jdk.runtime
Note: Some input files use unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
Compiling 744 files for java.xml.bind
Note: Some input files use or override a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
Note: Some input files use unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
Compiling 153 files for java.xml.soap
Compiling 777 files for jdk.xml.bind
.....

and so on.

Is this a bug ?

Also is there any equivalent of "JDK_FILTER=sun/java2d/cmm" so that I 
can build just
the files I know need to be rebuilt ? That seems to trigger a slew of 
errors for me now.

-phil.