QueryOnMetadata that uses Regular Expression did not work

[kazurayam]

I created in https://github.com/kazurayam/materialstore-tutorial/blob/develop/src/test/java/my/sample/T05SelectMaterialListTest.java

@Test
    public void test05_select_with_Regex() throws MaterialstoreException {
        JobName jobName = new JobName("test05_select_with_Regex");
        JobTimestamp jobTimestamp = JobTimestamp.now();
        SharedMethods.write3images(store, jobName, jobTimestamp);
        MaterialList materialList =
                store.select(jobName, jobTimestamp,
                        QueryOnMetadata.builder().put("label", "[a-z]+") // (21)
                                .build());
        assertEquals(2, materialList.size());
    }

I expected this test to pass, but it failed. The materialList.size() returned 0.

I specified a Regular Expression here:

QueryOnMetadata.builder().put("label", "[a-z]+")

It seems it does not work.

[kazurayam]

The following works

import java.util.regex.Pattern;
...
                        QueryOnMetadata.builder().put("label", Pattern.compile("[a-z]+")) // (21)
                                .build());