DATAKV-185 - Polishing.

Fix NPE by now returning an expression that always resolves to true.

Author: christophstrobl

src/main/java/org/springframework/data/keyvalue/repository/query/SpelQueryCreator.java

@@ -214,7 +214,7 @@ protected SpelExpression toPredicateExpression(PartTree tree) {
 			}
 		}
 
-		return !StringUtils.hasText(sb) ? null : PARSER.parseRaw(sb.toString());
+		return StringUtils.hasText(sb) ? PARSER.parseRaw(sb.toString()) : PARSER.parseRaw("true");
 	}
 
 	private static boolean requiresInverseLookup(Part part) {

src/test/java/org/springframework/data/keyvalue/repository/query/SpelQueryCreatorUnitTests.java

@@ -306,6 +306,13 @@ public void inMatchesNullValuesCorrectly() throws Exception {
 		assertThat(evaluate("findByFirstnameIn", list).against(new Person(null, 10)), is(true));
 	}
 
+	@Test // DATAKV-185
+	public void noDerivedQueryArgumentsMatchesAlways() throws Exception {
+
+		assertThat(evaluate("findBy").against(JON), is(true));
+		assertThat(evaluate("findBy").against(null), is(true));
+	}
+
 	private Evaluation evaluate(String methodName, Object... args) throws Exception {
 		return new Evaluation((SpelExpression) createQueryForMethodWithArgs(methodName, args).getCriteria());
 	}
@@ -336,6 +343,9 @@ private KeyValueQuery<SpelExpression> createQueryForMethodWithArgs(String method
 
 	static interface PersonRepository {
 
+		// No arguments
+		Person findBy();
+
 		// Type.SIMPLE_PROPERTY
 		Person findByFirstname(String firstname);