i have an problem while start up the application, In the process of encrypting some values in my database table - spring-boot

Question

This is the problem i get while i run my application:
Error creating bean with name 'aesEncryptor': Injection of autowired dependencies failed; nested exception is java.lang.IllegalArgumentException: Could not resolve placeholder 'aes.encryption.key' in value "${aes.encryption.key}"
Below is the code which is the class file in the application:
#Configuration
public class AesEncryptor implements AttributeConverter<Object, String> {
#Value("${aes.encryption.key}")
private String encryptionKey;
private final String encryptionCipher = "AES";
private Key key;
private Cipher cipher;
private Key getKey() {
if (key == null)
key = new SecretKeySpec(encryptionKey.getBytes(), encryptionCipher);
return key;
}
private Cipher getCipher() throws GeneralSecurityException {
if (cipher == null)
cipher = Cipher.getInstance(encryptionCipher);
return cipher;
}
private void initCipher(int encryptMode) throws GeneralSecurityException {
getCipher().init(encryptMode, getKey());
}
#SneakyThrows
#Override
public String convertToDatabaseColumn(Object attribute) {
if (attribute == null)
return null;
initCipher(Cipher.ENCRYPT_MODE);
byte[] bytes = SerializationUtils.serialize(attribute);
return Base64.getEncoder().encodeToString(getCipher().doFinal(bytes));
}
#SneakyThrows
#Override
public Object convertToEntityAttribute(String dbData) {
if (dbData == null)
return null;
initCipher(Cipher.DECRYPT_MODE);
byte[] bytes = getCipher().doFinal(Base64.getDecoder().decode(dbData));
return SerializationUtils.deserialize(bytes);
}
}