#2196 Implement equals() of query models in terms of tokens provide…

…d by the underlying token source

platform-pojo-bl/src/main/java/ua/com/fielden/platform/entity/query/model/AbstractModel.java

@@ -3,8 +3,6 @@
 import org.apache.commons.lang3.StringUtils;
 import ua.com.fielden.platform.eql.antlr.tokens.util.ListTokenSource;
 
-import java.util.Objects;
-
 import static java.lang.String.format;
 
 public abstract class AbstractModel {
@@ -22,13 +20,15 @@ public final ListTokenSource getTokenSource() {
     public int hashCode() {
         final int prime = 31;
         int result = 1;
-        result = prime * result + ((tokenSource == null) ? 0 : tokenSource.hashCode());
+        result = prime * result + ((tokenSource == null) ? 0 : tokenSource.tokens().hashCode());
         return result;
     }
 
     @Override
     public boolean equals(final Object obj) {
-        return this == obj || obj instanceof AbstractModel other && Objects.equals(tokenSource, other.tokenSource);
+        return this == obj || obj instanceof AbstractModel other &&
+                ((tokenSource == null && other.tokenSource == null) ||
+                        (tokenSource != null && other.tokenSource != null && tokenSource.equalTokens(other.tokenSource)));
     }
 
     @Override

platform-pojo-bl/src/main/java/ua/com/fielden/platform/eql/antlr/tokens/util/ListTokenSource.java

@@ -23,6 +23,9 @@ public ListTokenSource(final List<? extends Token> tokens, final String sourceNa
         super(tokens, sourceName);
     }
 
+    /**
+     * Returns a complete view on tokens provided by this source without advancing the current token position.
+     */
     public List<Token> tokens() {
         return unmodifiableList(tokens);
     }
@@ -36,4 +39,11 @@ public ListTokenSource restart() {
         return i == 0 ? this : new ListTokenSource(tokens, getSourceName());
     }
 
+    /**
+     * Determines whether this source provides the same tokens as the given one.
+     */
+    public boolean equalTokens(final ListTokenSource that) {
+        return tokens().equals(that.tokens());
+    }
+
 }