boolean (@Nullable GrExpression expression) { if (expression instanceof GrLiteral) { final String text = expression.getText(); if ("'".equals(GrStringUtil.getStartQuote(text))) return true; if ("\"".equals(GrStringUtil.getStartQuote(text))) return true; } else if (expression instanceof GrBinaryExpression) { final IElementType type = ((GrBinaryExpression)expression).getOperationTokenType(); if (type != GroovyTokenTypes.mPLUS) return false; final GrExpression left = ((GrBinaryExpression)expression).getLeftOperand(); final GrExpression right = ((GrBinaryExpression)expression).getRightOperand(); return containsOnlyLiterals(left) && containsOnlyLiterals(right); } return false; }