Fixed FlatFileItemReaderBuilder LineTokenizer validation

Fixed validation for the FlatFileItemReaderBuilder where no
LineTokenizer had been provided.

Resolves: #3688

Author: santfirax

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/file/builder/FlatFileItemReaderBuilder.java

@@ -469,7 +469,7 @@ public FlatFileItemReader<T> build() {
 			reader.setLineMapper(this.lineMapper);
 		}
 		else {
-			Assert.state(validatorValue == 1 || validatorValue == 2 || validatorValue == 4,
+			Assert.state(validatorValue == 0 || validatorValue == 1 || validatorValue == 2 || validatorValue == 4,
 					"Only one LineTokenizer option may be configured");
 
 			DefaultLineMapper<T> lineMapper = new DefaultLineMapper<>();

spring-batch-infrastructure/src/test/java/org/springframework/batch/item/file/builder/FlatFileItemReaderBuilderTests.java

@@ -541,6 +541,18 @@ public void testErrorMessageWhenNoFieldSetMapperIsProvided() {
 			assertEquals("No FieldSetMapper implementation was provided.", exceptionMessage);
 		}
 	}
+	@Test
+	public void testErrorMessageWhenNoLineTokenizerWasProvided() {
+		try {
+			new FlatFileItemReaderBuilder<Foo>()
+					.name("fooReader")
+					.resource(getResource("1;2;3"))
+					.build();
+		} catch (IllegalStateException exception) {
+			String exceptionMessage = exception.getMessage();
+			assertEquals("No LineTokenizer implementation was provided.", exceptionMessage);
+		}
+	}
 
 	private Resource getResource(String contents) {
 		return new ByteArrayResource(contents.getBytes());