ConstantMethodRef cannot be cast to class java.lang.String

I have been blocked...
I want to compile Java smart contract, is there any sample?
And the Picture is my code, I want to complie it to wasm. And happen following exceptions:

Exception in thread "main" de.inetsoftware.jwebassembly.WasmException: java.lang.ClassCastException: class de.inetsoftware.classparser.ConstantMethodRef cannot be cast to class java.lang.String (de.inetsoftware.classparser.ConstantMethodRef is in unnamed module of loader 'app'; java.lang.String is in module java.base of loader 'bootstrap')
at MyBank.createAccount(MyBank.java:19)
at de.inetsoftware.jwebassembly.WasmException.create(WasmException.java:145)
at de.inetsoftware.jwebassembly.WasmException.create(WasmException.java:118)
at de.inetsoftware.jwebassembly.WasmException.create(WasmException.java:99)
at de.inetsoftware.jwebassembly.module.JavaMethodWasmCodeBuilder.writeCode(JavaMethodWasmCodeBuilder.java:767)
at de.inetsoftware.jwebassembly.module.JavaMethodWasmCodeBuilder.buildCode(JavaMethodWasmCodeBuilder.java:99)
at de.inetsoftware.jwebassembly.module.ModuleGenerator.createInstructions(ModuleGenerator.java:586)
at de.inetsoftware.jwebassembly.module.ModuleGenerator.scanFunctions(ModuleGenerator.java:242)
at de.inetsoftware.jwebassembly.module.ModuleGenerator.prepareFinish(ModuleGenerator.java:325)
at de.inetsoftware.jwebassembly.JWebAssembly.compile(JWebAssembly.java:368)
at de.inetsoftware.jwebassembly.JWebAssembly.compileToText(JWebAssembly.java:279)
at de.inetsoftware.jwebassembly.JWebAssembly.compileToText(JWebAssembly.java:263)
at de.inetsoftware.jwebassembly.JWebAssembly.compileToText(JWebAssembly.java:229)
at Test.main(Test.java:31)
Caused by: java.lang.ClassCastException: class de.inetsoftware.classparser.ConstantMethodRef cannot be cast to class java.lang.String (de.inetsoftware.classparser.ConstantMethodRef is in unnamed module of loader 'app'; java.lang.String is in module java.base of loader 'bootstrap')
at de.inetsoftware.classparser.BootstrapMethod.(BootstrapMethod.java:58)
at de.inetsoftware.classparser.ClassFile.getBootstrapMethod(ClassFile.java:234)
at de.inetsoftware.jwebassembly.module.JavaMethodWasmCodeBuilder.writeCode(JavaMethodWasmCodeBuilder.java:662)
... 9 more