Document how APEXes are identified in the boot jar variables.

#################################################################

# Set up minimal BOOTCLASSPATH list of jars to build/execute

# java code with dalvikvm/art.

# Jars present in the ART apex. These should match exactly the list of

# Java libraries in the ART apex build rule.

# Jars present in the ART apex. These should match exactly the list of Java

# libraries in art-bootclasspath-fragment. The APEX variant name

# (com.android.art) is the same regardless which Soong module provides the ART

# APEX. See the long comment in build/soong/java/dexprepopt_bootjars.go for

# details.

ART_APEX_JARS := \

    com.android.art:core-oj \

    com.android.art:core-libart \

# The list of product-specific kernel header dirs

_product_list_vars += PRODUCT_VENDOR_KERNEL_HEADERS

# A list of module names of BOOTCLASSPATH (jar files)

# A list of module names in BOOTCLASSPATH (jar files). Each module may be

# prefixed with "<apex>:", which identifies the APEX that provides it. APEXes

# are identified by their "variant" names, i.e. their `apex_name` values in

# Soong, which default to the `name` values. The prefix can also be "platform:"

# or "system_ext:", and defaults to "platform:" if left out. See the long

# comment in build/soong/java/dexprepopt_bootjars.go for details.

_product_list_vars += PRODUCT_BOOT_JARS

# A list of extra BOOTCLASSPATH jars (to be appended after common jars).

# Products that include device-specific makefiles before AOSP makefiles should use this

# instead of PRODUCT_BOOT_JARS, so that device-specific jars go after common jars.

# A list of extra BOOTCLASSPATH jars (to be appended after common jars),

# following the same format as PRODUCT_BOOT_JARS. Products that include

# device-specific makefiles before AOSP makefiles should use this instead of

# PRODUCT_BOOT_JARS, so that device-specific jars go after common jars.

_product_list_vars += PRODUCT_BOOT_JARS_EXTRA

_product_single_value_vars += PRODUCT_SUPPORTS_BOOT_SIGNER

_product_single_value_vars += PRODUCT_BUILD_VBMETA_IMAGE

_product_single_value_vars += PRODUCT_BUILD_SUPER_EMPTY_IMAGE

# List of boot jars delivered via apex

# List of boot jars delivered via updatable APEXes, following the same format as

# PRODUCT_BOOT_JARS.

_product_list_vars += PRODUCT_UPDATABLE_BOOT_JARS

# If set, device uses virtual A/B.