CombinedCheckState: remove the "passing" boolean

Given those ancestor commits, this boolean field
isn't useful any more.

Change-Id: I78af77a4c0f99c0743f04f51c7cdaa25b622576e
diff --git a/java/com/google/gerrit/plugins/checks/api/BlockingCondition.java b/java/com/google/gerrit/plugins/checks/api/BlockingCondition.java
index f0d032d..6ba3769 100644
--- a/java/com/google/gerrit/plugins/checks/api/BlockingCondition.java
+++ b/java/com/google/gerrit/plugins/checks/api/BlockingCondition.java
@@ -21,10 +21,7 @@
  * blocks submission of a change.
  */
 public enum BlockingCondition {
-  /**
-   * Block submission unless the combined state for all checks on the change {@link
-   * CombinedCheckState#isPassing() is passing}.
-   */
+  /** Block submission unless all required checks on the change is passing. */
   STATE_NOT_PASSING;
 
   public static Boolean isRequired(Set<BlockingCondition> blocking) {
diff --git a/java/com/google/gerrit/plugins/checks/api/CombinedCheckState.java b/java/com/google/gerrit/plugins/checks/api/CombinedCheckState.java
index 0975441..b50a41a 100644
--- a/java/com/google/gerrit/plugins/checks/api/CombinedCheckState.java
+++ b/java/com/google/gerrit/plugins/checks/api/CombinedCheckState.java
@@ -29,28 +29,26 @@
  */
 public enum CombinedCheckState {
   /** At least one required check failed; other checks may have passed, or still be running. */
-  FAILED(false),
+  FAILED,
 
   /**
    * All relevant checks terminated, and at least one optional check failed, but no required checks
    * failed.
-   *
-   * <p>This state is considered {@link #isPassing() passing}, as in "checks passed with warnings."
    */
-  WARNING(true),
+  WARNING,
 
   /**
    * At least one relevant check is in a non-terminated state ({@link CheckState#NOT_STARTED},
    * {@link CheckState#SCHEDULED}, {@link CheckState#RUNNING}), and no required checks failed. Some
    * optional checks may have failed.
    */
-  IN_PROGRESS(false),
+  IN_PROGRESS,
 
   /** All relevant checks terminated successfully. */
-  SUCCESSFUL(true),
+  SUCCESSFUL,
 
   /** No checks are relevant to this change. */
-  NOT_RELEVANT(true);
+  NOT_RELEVANT;
 
   /**
    * Combines multiple per-check states into a single combined state.
@@ -97,24 +95,6 @@
     return NOT_RELEVANT;
   }
 
-  private final boolean passing;
-
-  CombinedCheckState(boolean passing) {
-    this.passing = passing;
-  }
-
-  /**
-   * Returns whether the state represents a passing state.
-   *
-   * <p>A passing state is one that is either completed successfully with or without warnings
-   * ({@link #WARNING} or {@link #SUCCESSFUL}), or is simply {@link #NOT_RELEVANT}.
-   *
-   * @return whether the state represents a passing state.
-   */
-  public boolean isPassing() {
-    return passing;
-  }
-
   @AutoValue
   public abstract static class CheckStateCount {
     /**