DATAJDBC-355 - Remove unnecessary null check.

The source parameter must not be null according to Javadoc of Converter.

See also: https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/core/convert/converter/Converter.html

Original pull request: #146.

Author: benelog

spring-data-jdbc/src/test/java/org/springframework/data/jdbc/repository/JdbcRepositoryCustomConversionIntegrationTests.java

@@ -39,7 +39,6 @@
 import org.springframework.data.jdbc.repository.support.JdbcRepositoryFactory;
 import org.springframework.data.jdbc.testing.TestConfiguration;
 import org.springframework.data.repository.CrudRepository;
-import org.springframework.lang.Nullable;
 import org.springframework.test.context.ContextConfiguration;
 import org.springframework.test.context.junit4.rules.SpringClassRule;
 import org.springframework.test.context.junit4.rules.SpringMethodRule;
@@ -49,6 +48,7 @@
  * Tests storing and retrieving data types that get processed by custom conversions.
  *
  * @author Jens Schauder
+ * @author Sanghyuk Jung
  */
 @ContextConfiguration
 @Transactional
@@ -93,9 +93,9 @@ JdbcCustomConversions jdbcCustomConversions() {
 	 *
 	 * 	@Override
 	 * 	@Nullable
-	 * 	public BigDecimal convert(@Nullable String source) {
+	 * 	public BigDecimal convert(String source) {
 	 *
-	 * 		return source == null ? null : new BigDecimal(source);
+	 * 		return source == new BigDecimal(source);
 	 * 	}
 	 * }
 	 * </pre>
@@ -130,9 +130,9 @@ enum StringToBigDecimalConverter implements Converter<String, JdbcValue> {
 		INSTANCE;
 
 		@Override
-		public JdbcValue convert(@Nullable String source) {
+		public JdbcValue convert(String source) {
 
-			Object value = source == null ? null : new BigDecimal(source);
+			Object value = new BigDecimal(source);
 			return JdbcValue.of(value, JDBCType.DECIMAL);
 		}
 
@@ -144,11 +144,7 @@ enum BigDecimalToString implements Converter<BigDecimal, String> {
 		INSTANCE;
 
 		@Override
-		public String convert(@Nullable BigDecimal source) {
-
-			if (source == null) {
-				return null;
-			}
+		public String convert(BigDecimal source) {
 
 			return source.toString();
 		}