[yocto] do all recipes really need LIC_FILES_CHKSUM?

[Robert P. J. Day]

  current poky ref manual seems pretty adamant about need for
LIC_FILES_CHKSUM:

"Note that this variable is mandatory for all recipes, unless the
LICENSE variable is set to "CLOSED".

but there's at least one counter-example,
meta-demoapps/recipes-graphics/pong-clock/pong-clock_1.0.bb:

=====

DESCRIPTION = "A clock combined with a game of pong"
LICENSE = "GPLv2+"
DEPENDS = "virtual/libx11 xdmcp xau"

SRC_URI = "file://pong-clock-no-flicker.c"

S = "${WORKDIR}"

do_compile () {
        ${CC} -o pong-clock pong-clock-no-flicker.c `pkg-config --cflags --libs x11 xau xdmcp`
}

do_install () {
        install -d ${D}${bindir}
        install -m 0755 pong-clock ${D}${bindir}
}

=====

so what's the story here?

rday

-- 

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Robert P. J. Day                                 Ottawa, Ontario, CANADA
                        http://crashcourse.ca

Twitter:                                       http://twitter.com/rpjday
LinkedIn:                               http://ca.linkedin.com/in/rpjday
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