usage:
pdf2img [-b64 | -o <outputDirectory> [-f <format>]] <inputFiles>

 -?,--help           Print this message.
 -b64,--base64       Base64 format output.
 -f,--format <arg>   Output file format. Select from "png" or "jpg".
 -o,--out <arg>      Output directory.

$ ls /dir/path
A.pdf   B.pdf

$ java -jar pdf2img.jar -o /dir/path /dir/path/A.pdf /dir/path/B.pdf

$ ls /dir/path
A.pdf   A.png   B.pdf   B.png

$ ls /dir/path
A.pdf   B.pdf

$ ./mvnw clean spring-boot:run -U -Drun.arguments=-o,/dir/path,/dir/path/A.pdf,/dir/path/B.pdf

$ ls /dir/path
A.pdf   A.png   B.pdf   B.png