--- old/make/windows/makefiles/rules.make	2020-01-16 16:56:27.835551628 +0300
+++ new/make/windows/makefiles/rules.make	2020-01-16 16:56:27.787553177 +0300
@@ -44,8 +44,14 @@
 !endif
 
 # Settings for javac
+!if "$(ENABLE_JFR)" == "true"
+# JFR source code is consciously left as close as possible to later versions of JDK. hence need at least lambda support
 BOOT_SOURCE_LANGUAGE_VERSION=8
 BOOT_TARGET_CLASS_VERSION=8
+!else
+BOOT_SOURCE_LANGUAGE_VERSION = 7
+BOOT_TARGET_CLASS_VERSION = 7
+!endif
 JAVAC_FLAGS=-g -encoding ascii
 BOOTSTRAP_JAVAC_FLAGS=$(JAVAC_FLAGS) -source $(BOOT_SOURCE_LANGUAGE_VERSION) -target $(BOOT_TARGET_CLASS_VERSION)