Tower Heist

Josh Kovaks is the building manager of The Tower, a luxury apartment complex in New York City whose employees include concierge Charlie, who is expecting a child with Josh's sister; Enrique, a newly hired elevator operator; Lester, the doorman nearing retirement; Odessa, an immigrant maid from Jamaica; and receptionist Miss Iovenko, who is studying to become a lawyer.
One morning Josh sees Arthur Shaw, a wealthy Tower resident, being kidnapped. Josh gives chase, but is tackled by FBI agent Claire Denham, who explains that Shaw was attempting to flee the country and avoid arrest for embezzling $2 billion in a Ponzi scheme. Josh confesses to the Tower staff that he gave their pensions to Shaw to invest, and they have lost everything; Lester attempts suicide. After visiting Lester in hospital, Josh, Charlie, and Enrique confront Shaw, under house arrest in his penthouse apartment. Shaw's insincere condolences enrage Josh and he smashes the windows of the 1963 Ferrari 250 GT Lusso displayed in Shaw's apartment. Josh, Charlie, and Enrique are fired for the incident.
Josh meets Denham at a bar where she suggests that Shaw has concealed $20 million as a reserve, and that Josh should steal it. Josh, Charlie, Enrique, and evicted Tower tenant Mr. Fitzhugh conspire to find and steal the money from Shaw's assumed safe. They supplement their inexperience by enlisting Josh's childhood former friend Slide, a petty criminal, and Odessa, who has locksmith experience that can help open the safe. Charlie is later rehired as the Tower's new manager, and warns Josh to abandon the plan or he will inform the police. Subsequently, Denham informs Josh that Shaw is scheduled for to attend court on Thanksgiving during the Macy's Thanksgiving Day Parade to avoid publicity, and that Shaw will be set free. Josh and his team decide to break into Shaw's apartment during the parade.
Slide attempts to betray the team by reaching the safe first, having tricked Odessa into giving him lessons. The team intercepts him at Shaw's apartment, and during the ensuing struggle they break down a false wall, revealing Shaw's empty safe. Slide and Fitzhugh struggle for Slide's gun; the gun goes off and the bullet hits the car, revealing gold underneath the Ferrari's paint. They realize that Shaw used his money to buy gold, turn it into car parts, and assembled the car to hide the money in plain sight. Josh finds a ledger of Shaw's illegal finances in the car's glove box. They use a window-washing platform to lower the car from the apartment into an empty apartment below before lowering it to the lobby on top of the elevator. As they reach the lobby, Denham and Shaw return, revealing the Thanksgiving court date as a ruse as part of the plan. Denham notes the missing car and Shaw's safe and rearrests him for violating his bail by not declaring the latter.
Denham and the FBI arrest Josh and the crew (except Slide) as they walk outside the Tower. Miss Iovenko arrives, telling the FBI that she passed her bar exam three days ago and is acting as Josh's attorney. She shows them Shaw's ledger and tells them she will turn it over in exchange for everyone's freedom. The FBI accepts on the condition that Josh, being the primary conspirator, must serve a minimal two-year sentence, but Denham lowers it to 16 months to make sure Josh gets out for good behavior. Shaw is convicted and sentenced to prison for the rest of his life.
The team retrieves the car from its hiding place in Shaw's rooftop pool and send various parts of the car to Tower employees to compensate for their lost pensions. As Josh is led to his cell, a satisfied smile slowly forms on his face.

Question: What is revealed when the false wall is broken at Shaw's apartment?
Answer: An empty safe