Fix failing UTs

Author: julian-elastic

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/enrich/ExpressionQueryList.java

@@ -85,8 +85,8 @@ private void buildPrePostJoinFilter(PhysicalPlan rightPreJoinPlan, ClusterServic
             } catch (IOException e) {
                 throw new IllegalArgumentException("Failed to translate pre-join filter: " + esQueryExec, e);
             }
-        } else {
-            throw new IllegalArgumentException("Unsupported pre-join filter type: " + preJoinFilters.getClass().getName());
+        } else if (rightPreJoinPlan != null) {
+            throw new IllegalArgumentException("Unsupported pre-join filter type: " + rightPreJoinPlan.getClass().getName());
         }
     }
 

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/enrich/LookupFromIndexOperator.java

@@ -62,7 +62,7 @@ public String describe() {
                     .append(" inputChannel=")
                     .append(matchField.channel());
             }
-            stringBuilder.append(" rightPreJoinPlan=").append(rightPreJoinPlan);
+            stringBuilder.append(" right_pre_join_plan=").append(rightPreJoinPlan);
             stringBuilder.append("]");
             return stringBuilder.toString();
         }

x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/enrich/LookupFromIndexOperatorTests.java

@@ -187,7 +187,7 @@ protected Matcher<String> expectedToStringOfSimple() {
         for (int i = 0; i < numberOfJoinColumns; i++) {
             sb.append(" input_type=LONG match_field=match").append(i).append(" inputChannel=").append(i);
         }
-        sb.append("]");
+        sb.append(" right_pre_join_plan=null]");
         return matchesPattern(sb.toString());
     }
 

x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/optimizer/LogicalPlanOptimizerTests.java

@@ -7055,7 +7055,9 @@ public void testLookupJoinPushDownSeparatedForConjunctionBetweenLeftAndRightFiel
         assertThat(literal.value(), equalTo(1));
 
         var leftRel = as(filter.child(), EsRelation.class);
-        var rightRel = as(join.right(), EsRelation.class);
+        var filterRight = as(join.right(), Filter.class);
+        assertEquals("language_name == \"English\"", filterRight.condition().toString());
+        var rightRel = as(filterRight.child(), EsRelation.class);
     }
 
     /**