about JEXL and replacing in SelectVariants()

Dear all, good afternoon. I would appreciate please an insight on the following : I am using SelectVariants to select the HETEROZYG and it is working :

$GATK \
-T SelectVariants \
-R $REFERENCE_HG38_MALE \
-select 'vc.getGenotype("040_7G").isHet()' \
-V 7G.GRCh38p5M.MD_samtools.germline.HETERO.chr19.vcf \
-o 7G.GRCh38p5M.MD_samtools.germline.HETERO.chr19.vcf.HET2.vcf

As the name of the sample (in the FORMAT field) is "040_7G", would like to change the NAME of the SAMPLE in vc.getGenotype("040_7G") with a VARIABLE called SAMPLE. How shall I do that :

SAMPLE="\"040_7G\"" and -select 'vc.getGenotype("${SAMPLE}").isHet()' does not really work ... Thank you, and happy Easter !