Merge "Update a comment about PRODUCT_UPDATABLE_BOOT_JARS."

// library is a part of a non-updatable APEX).

//

// A related variable PRODUCT_UPDATABLE_BOOT_JARS contains bootclasspath libraries that are in

// updatable APEXes. They are not included in the boot image.

// APEXes. They are not included in the boot image. The only exception here is core-icu4j.jar that

// has been historically part of the boot image and is now in a non updatable apex; it is treated

// as being part of PRODUCT_BOOT_JARS and is in the boot image.

//

// One exception to the above rules are "coverage" builds (a special build flavor which requires

// setting environment variable EMMA_INSTRUMENT_FRAMEWORK=true). In coverage builds the Java code in