The next line does not work well if jdk11.0.18 is used:
SUPPORT_OLD_SOURCE_TARGET = $(shell $(JDKJAVAC) -version 2>&1 | grep '[8]' > /dev/null && echo true )
SUPPORT_OLD_SOURCE_TARGET = $(shell $(JDKJAVAC) -version 2>&1 | grep '[8]' > /dev/null && echo true )