InstructionDB getInstructionAt(long addr) {
		if (addr == AddressMap.INVALID_ADDRESS_KEY) {
			return null;
		}
		lock.acquire();
		try {
			CodeUnitDB cu = cache.get(addr);
			if (cu == null) {
				return getInstructionDB(addr);
			}
			else if (cu instanceof InstructionDB) {
				return (InstructionDB) cu;
			}
		}
		catch (IOException e) {
			program.dbError(e);
		}
		finally {
			lock.release();
		}
		return null;
	}
Returns the instruction whose min address equals the specified address or null if the 
address is not the beginning address of some code unit.

@param address the min address of the instruction to return

@return the instruction at the specified address, or null if a instruction does not 
exist starting at the given address.
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/code/CodeManager.java