Java: Add a test for java/suspicious-date-format.

Author: chrisgavin

java/ql/test/query-tests/SuspiciousDateFormat/A.java

@@ -0,0 +1,10 @@
+import java.text.SimpleDateFormat;
+import java.util.Date;
+
+public class A {
+	public static void main(String[] args) {
+		System.out.println(new SimpleDateFormat("yyyy-MM-dd").format(new Date())); // OK
+		System.out.println(new SimpleDateFormat("YYYY-ww").format(new Date())); // OK
+		System.out.println(new SimpleDateFormat("YYYY-MM-dd").format(new Date())); // BAD
+	}
+}

java/ql/test/query-tests/SuspiciousDateFormat/SuspiciousDateFormat.expected

@@ -0,0 +1 @@
+| A.java:8:22:8:55 | new SimpleDateFormat(...) | Date formatter is passed a suspicious pattern "YYYY-MM-dd". |

java/ql/test/query-tests/SuspiciousDateFormat/SuspiciousDateFormat.qlref

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+Likely Bugs/Likely Typos/SuspiciousDateFormat.ql