Rename the thread local var

Signed-off-by: Lantao Jin <ltjin@amazon.com>

Author: LantaoJin

core/src/main/java/org/opensearch/sql/calcite/CalcitePlanContext.java

@@ -36,7 +36,7 @@ public class CalcitePlanContext {
   public final QueryType queryType;
   public final Integer querySizeLimit;
 
-  public static final ThreadLocal<Boolean> isExplain = ThreadLocal.withInitial(() -> false);
+  public static final ThreadLocal<Boolean> skipEncoding = ThreadLocal.withInitial(() -> false);
 
   @Getter @Setter private boolean isResolvingJoinCondition = false;
   @Getter @Setter private boolean isResolvingSubquery = false;

opensearch/src/main/java/org/opensearch/sql/opensearch/executor/OpenSearchExecutionEngine.java

@@ -172,7 +172,7 @@ public void explain(
               try (Hook.Closeable closeable = getPhysicalPlanInHook(physical, level)) {
                 if (format == ExplainFormat.EXTENDED) {
                   getCodegenInHook(javaCode);
-                  CalcitePlanContext.isExplain.set(true);
+                  CalcitePlanContext.skipEncoding.set(true);
                 }
                 // triggers the hook
                 AccessController.doPrivileged(
@@ -186,7 +186,7 @@ public void explain(
           } catch (Exception e) {
             listener.onFailure(e);
           } finally {
-            CalcitePlanContext.isExplain.remove();
+            CalcitePlanContext.skipEncoding.remove();
           }
         });
   }

opensearch/src/main/java/org/opensearch/sql/opensearch/storage/serde/RelJsonSerializer.java

@@ -95,7 +95,7 @@ public String serialize(
       ObjectOutputStream objectOutput = new ObjectOutputStream(output);
       objectOutput.writeObject(envelope);
       objectOutput.flush();
-      return CalcitePlanContext.isExplain.get()
+      return CalcitePlanContext.skipEncoding.get()
           ? rexNodeJson
           : Base64.getEncoder().encodeToString(output.toByteArray());
     } catch (Exception e) {