public Builder docRef(final DocRef value) {
            this.docRef = value;
            return this;
        }
Add a entity term to the builder, e.g fieldX|IS_DOC_REF|docRefToDictionaryY
Term is enabled by default. Not all data sources support entity terms and only certain
conditions are supported for an entity term.

@param value The DocRef for the entity that this predicate is using for its evaluation
@return The {@link Builder}, enabling method chaining
stroom-legacy/stroom-legacy-model_6_1/src/main/java/stroom/legacy/model_6_1/ExpressionTerm.java