Add Converter

src/main/kotlin/org/octopus/internal/db/converters/MonthListConverter.kt

@@ -0,0 +1,19 @@
+package org.octopus.internal.db.converters
+
+import jakarta.persistence.AttributeConverter
+import jakarta.persistence.Converter
+import java.time.Month
+
+@Converter
+class MonthListConverter : AttributeConverter<List<Month>, String> {
+
+    override fun convertToDatabaseColumn(attribute: List<Month>?): String? {
+        return attribute?.joinToString(separator = ",") { it.name }
+    }
+
+    override fun convertToEntityAttribute(dbData: String?): List<Month>? {
+        return dbData?.split(",")
+            ?.filter { it.isNotBlank() }
+            ?.mapNotNull { runCatching { Month.valueOf(it.trim()) }.getOrNull() }
+    }
+}