public void test_multipleOperations() {
        // Add initial values
        dataStoreParams.put("key1", "value1");
        dataStoreParams.put("key2", 123);

        // Add more values using putAll
        Map<String, String> additionalParams = new HashMap<>();
        additionalParams.put("key3", "value3");
        additionalParams.put("key4", "value4");
        dataStoreParams.putAll(additionalParams);

        value = "  key1  =  value1  \n  key2=value2\n";
        paramMap = ParameterUtil.parse(value);
        assertEquals(2, paramMap.size());
        assertEquals("value1", paramMap.get("key1"));
        assertEquals("value2", paramMap.get("key2"));

        // Test with empty lines and mixed whitespace
        value = "key1=value1\n\n\t\nkey2=value2\n \n";
        paramMap = ParameterUtil.parse(value);

        docMap.put("key1", "value1");
        docMap.put("key2", "value2");
        docMap.put("key3", "value3");

        Collection<Object> values = docMap.values();
        assertEquals(3, values.size());
        assertTrue(values.contains("value1"));
        assertTrue(values.contains("value2"));
        assertTrue(values.contains("value3"));
    }

        value = " value1 , value2 , value3 ";
        result = KuromojiCSVUtil.parse(value);
        assertEquals(3, result.length);
        assertEquals(" value1 ", result[0]);
        assertEquals(" value2 ", result[1]);
        assertEquals(" value3 ", result[2]);

        // Spaces in quoted values
        value = "\" spaced value \",\"  another  \"";
        result = KuromojiCSVUtil.parse(value);

        // Test getting multiple different properties
        String value1 = fessConfig.get("domain.title");
        String value2 = fessConfig.get("search_engine.type");

        assertEquals("Test Fess", value1);
        assertEquals("opensearch", value2);
        assertFalse(value1.equals(value2));
    }

    // Test empty string property value
    public void test_get_emptyStringValue() {

        // Test minimum value
        event.setVersionNo(Long.MIN_VALUE);
        assertEquals(Long.valueOf(Long.MIN_VALUE), event.getVersionNo());

        // Test zero
        event.setVersionNo(0L);
        assertEquals(Long.valueOf(0L), event.getVersionNo());

        // Test maximum value
        event.setVersionNo(Long.MAX_VALUE);
        assertEquals(Long.valueOf(Long.MAX_VALUE), event.getVersionNo());

    checkNotNull(value2);
    checkArgument(!Objects.equals(value1, value2), "Duplicate value provided.");
    distinctValues.replaceValues(type, ImmutableList.of(value1, value2));
    setDefault(type, value1);
    return this;
  }

  /**
   * Tests that {@code cls} properly checks null on all constructor and method parameters that
   * aren't annotated nullable (according to the rules of {@link NullPointerTester}). In details:
   *

        System.setProperty("custom.prop.one", "value1");
        System.setProperty("custom.prop.two", "value2");
        System.setProperty("other.property", "value3");

        // Test with regex pattern
        execJob.testAddFessCustomSystemProperties(cmdList, "custom\\.prop\\..*");

        assertEquals(2, cmdList.size());
        assertTrue(cmdList.contains("-Dcustom.prop.one=value1"));

    checkNotNull(value2);
    checkArgument(!Objects.equals(value1, value2), "Duplicate value provided.");
    distinctValues.replaceValues(type, ImmutableList.of(value1, value2));
    setDefault(type, value1);
    return this;
  }

  /**
   * Tests that {@code cls} properly checks null on all constructor and method parameters that
   * aren't annotated nullable (according to the rules of {@link NullPointerTester}). In details:
   *

    }

    static final class DuplicateKey {
      private final Object key;
      private final Object value1;
      private final Object value2;

      DuplicateKey(Object key, Object value1, Object value2) {
        this.key = key;
        this.value1 = value1;
        this.value2 = value2;
      }

      IllegalArgumentException exception() {
        return new IllegalArgumentException(