#1427 - QueryCache should be cleared, if one of a dependent bean is updated

Initial work, does not include propagation across cluster.

src/test/java/io/ebeaninternal/server/transaction/TableModStateTest.java

@@ -0,0 +1,44 @@
+package io.ebeaninternal.server.transaction;
+
+import org.junit.Test;
+
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Set;
+
+import static org.junit.Assert.*;
+
+public class TableModStateTest {
+
+  private TableModState tableModState = new TableModState();
+
+  @Test
+  public void isValid() {
+
+    long now = System.currentTimeMillis();
+
+    tableModState.touch(setOf("one", "two", "three"), now);
+
+    // empty
+    assertTrue(tableModState.isValid(Collections.emptySet(), 12L));
+
+    // no entry
+    assertTrue(tableModState.isValid(setOf("noEntry"), 12L));
+
+    // later timestamp
+    assertTrue(tableModState.isValid(setOf("one"), now + 1));
+    assertTrue(tableModState.isValid(setOf("one", "two", "noEntry"), now + 1));
+
+    // invalid
+    assertFalse(tableModState.isValid(setOf("one"), now - 1));
+    assertFalse(tableModState.isValid(setOf("one", "two"), now - 1));
+    assertFalse(tableModState.isValid(setOf("three", "two"), now - 1));
+
+  }
+
+  private Set<String> setOf(String... tables) {
+    Set<String> touched = new HashSet<>();
+    Collections.addAll(touched, tables);
+    return touched;
+  }
+}