add logical operator in hypertrace gql common schema (#165)

Author: bhubam

hypertrace-core-graphql-common-schema/src/main/java/org/hypertrace/core/graphql/common/schema/operator/LogicalOperator.java

@@ -0,0 +1,12 @@
+package org.hypertrace.core.graphql.common.schema.operator;
+
+import graphql.annotations.annotationTypes.GraphQLDescription;
+import graphql.annotations.annotationTypes.GraphQLName;
+
+@GraphQLDescription("Logical operator describing how to combine multiple independent clauses")
+@GraphQLName(LogicalOperator.TYPE_NAME)
+public enum LogicalOperator {
+  AND,
+  OR;
+  static final String TYPE_NAME = "LogicalOperator";
+}